Employment 6. Topographical Anatomy of Abdominal Cavity. Topographical Anatomy of Abdominal Cavity Organs. Operations on Abdominal Cavity Organs. Intestinal Sutures. Resection of Intestine. Operation Interventions on the Stomach. Operation Interventions on the Liver, Gall Bladder, Biliary Tracts, Pancreas. Appendectomy. Operation Interventions on the Large Intestine.
STOMACH (VENTRICULUS OR GASTER)
EMBRYOLOGY To understand thoroughly the surgical anatomy of the stomach and the maneuvers necessary for good surgical exposure, the embryology must be understood. The stomach is developed from that part of the foregut which is situated between the esophagus and the pharynx in front and the liver bud and the yolk sac behind. During the 4th week, the stomach is located in the neck; at that time, the heart, the lungs and the stomach all lie near the exit of the vagal fibers from the central nervous system. During the 6th and the 7th week the growth of the lung buds causes an elongation of the esophagus and a backward migration of the stomach so that it changes from a cervical structure to one which is located in the lower thorax. This organ, whose embryologic position has its long axis in the median plane and its greater curvature facing dorsally, changes its position so that in the fully developed stage it becomes almost transversely placed with its greater curvature facing downward and to the left and its lesser curvature facing upward and to the right. This change is brought about by two combined axial rotations: the first takes place about the long axis of the stomach and the second about the anteroposterior axis. The first rotation (longitudinal axis) swings through an arc of 90°; as a result of this, the primitive left gastric surface is directed forward; the primitive right gastric surface, backward; the greater curvature with its attached dorsal mesogastrium, to the left; and the lesser curvature with its attached ventral mesogastrium, to the right. The lesser peritoneal cavity (omental bursa) now forms a retrogastric pouch; the spleen and the splenic artery are on the left; and the meso-esophagus has become so shortened that the esophagus lies almost against the posterior wall. The second rotation (anteroposterior axis) draws the pyloric end of the stomach to the right and the cardiac end to the left. The opening into the lesser sac is formed and is known as the epiploic foramen (of Winslow).
ADULT STOMACH The stomach is the most dilated part of the digestive tube. It is approximately
FIG. Embryology of the stomach. (A) Early development of the stomach as it is situated between the two leaves of peritoneum which form the dorsal and the ventral mesogastria. (B) After the first rotation (longitudinal axis) in which the stomach swings through an arc of 90°. The omental bursa is formed. (C) After the second rotation (anteroposterior axis); this draws the pyloric end of the stomach to the right and the cardiac end to the left. (D) After rotation is completed, and with the distal portion of the stomach removed to show the peritoneal relations.
to its right, the esophageal branches of the left gastric vessels. The pyloric orifice is the communication between the stomach and the duodenum (duodenopyloric junction). This opening lies
FIG. The adult stomach.
the transverse mesocolon. Above the transverse mesocolon, the stomach is in contact with the anterior surface of the pancreas; above the pancreas, the stomach lies to the left of the median plane and rests on the upper part of the left kidney and the left suprarenal gland. At a still higher level, the stomach (fundus) occupies the concave gastric area of the spleen and comes into relationship with the left half of the diaphragm. The normal stomach is separated anteriorly and posteriorly from the neighboring organs only by capillary spaces; this separation is effected in such a manner that direct contact is made. The 2 curvatures are the lesser on the right and the greater on the left. The lesser curvature extends between the cardiac and the pyloric orifices. It has vertical and horizontal parts which join at the incisura angularis and form a concave border in the form of a letter “J.” This curvature is continuous with the right margin of the esophagus and normally is overlapped by the liver. It affords attachment for the lesser omentum (gastrohepatic part) and contains the arterial circle formed by the right and the left gastric arteries. The greater curvature is convex and is 4 or 5 times as long as the lesser. Its upper third is directed toward the left; the middle third, downward and to the left; and the lower third, downward and to the right. It starts at the incisura cardiaca, passes upward as high as the 6th left costal cartilage and ends at the pylorus. Along the lower part of the greater curvature, the 2 layers of peritoneum which envelop the stomach pass downward as the greater omentum; on the left, they pass backward toward the spleen as the gastrosplenic ligament. Although the lesser curvature is comparatively fixed owing to its attachments, the greater curvature is freely movable, and its position alters as the stomach becomes full or empty, contracted or relaxed. When an individual is standing, the greater curvature may descend to the umbilicus or below it, but when lying down, it is an inch or more above the umbilicus. In ptosis, the curvatures become more nearly vertical in position, and both curvatures descend; but in gastric dilatation the greater curvature is lower, without altering the position of the somewhat fixed lesser curvature. The right and the left gastroepiploic vessels form an arterial circle as they separate the 2 layers of peritoneum which are attached here. The fundus is the rounded uppermost part of the stomach which is situated above the level of the esophageal junction; during life, it probably always contains gas. It bulges upward into the left cupola of the diaphragm as high as the level of the 5th costal cartilage and, therefore, is related to the heart, the pericardium and the left lung. This partly explains the increased cardiac activity and the accelerated respirations which are produced by the upward pressure of a full or distended stomach. The top of the fundus is almost on a level with the left male nipple. The body of the stomach is the main portion which lies between the incisura angularis and the incisura cardiaca (between the fundus and the pylorus). Its general direction is oblique and to the left. The pylorus is the point of junction between the stomach and the duodenum. The outer surface of the pylorus is marked by a circular constriction (duodenopyloric constriction). It lies in the transpylo ric plane, about
FIG. Arterial supply of the stomach. (A) The lesser omentum has been removed, and a wedge of greater omentum has been lifted to show the relations of the vessels. (B) The stomach has been elevated so that the posterior gastric surface is viewed.
FIG. Veins of the stomach. (A) The liver has been sectioned to show the venous relations. (B) The distal four fifths of the stomach and part of the pancreas have been removed.
rest of the stomach because of an increase in the circular muscle fibers. This thick muscular ring closes and relaxes the pyloric orifice and forms the pyloric sphincter. Normally, the pylorus is in a closed state, but when open it is capable of admitting a fingertip. Despite its narrowness, many cases are reported in which foreign bodies as large as pencils, forks, keys, etc. have been passed through it. Behind, it is related to the portal vein, the hepatic artery and the common duct. Two layers of peritoneum envelop the stomach; at the lesser curvature these meet and pass upward as the lesser omentum, which becomes attached to the liver and the diaphragm. This omentum has 2 parts: the gastrohepatic and the duodenohepatic. The gastrohepatic part is avascular, thin, transparent and contains no important structures. The duodenohepatic part of the lesser omentum is thick and contains 3 vital structures: the common duct, the portal vein and the hepatic artery. The 2 layers of peritoneum which clothe the stomach meet at the greater curvature and pass downward as one great fold. Different parts of this fold receive different names according to their attachments: the gastrohepatic ligament is attached to the diaphragm; the gastrosplenic ligament, to the spleen; and the greater omentum, to the transverse colon. That portion of greater omentum which is situated between the stomach and the transverse colon is known as the gastrocolic ligament (see Peritoneum.
VESSELS AND NERVES
The arterial supply to the stomach is derived from the celiac axis. The lesser curvature is supplied by the left gastric (coronary) artery which reaches the cardiac end of the curvature along the left edge of the gastrohepatic omentum. It passes upward and to the left on the left eras of the diaphragm, and then it turns over the upper border of the lesser sac to reach the stomach. It continues downward, forward and to the right, and passes along the curvature to anastomose with the right gastric (pyloric) artery, a branch of the hepatic. The greater curvature is supplied by the following arteries: The vasa brevia (short gastric), which are usually 4 or
The veins of the stomach correspond to the arteries; they terminate in the portal vein or the 2 large vessels which form it (superior mesenteric and splenic veins). They form 2 great loops: the one along the lesser curvature and the other along the greater. Associated with these are some short gastric veins at the fundus. The loop on the lesser curvature is made up of the left gastric (coronary) and the right gastric veins. The left gastric vein accompanies the left gastric artery along the lesser curvature and receives tributaries from both surfaces of that organ and also from the esophagus. It continues backward in the left gastropancreatic fold to the posterior wall of the abdomen; then it turns downward and to the right and empties into the portal vein. The right gastric vein passes to the right along the lesser curvature of the stomach and at the pylorus turns backward and enters the portal vein. It receives venous blood from both surfaces of the stomach and from a vein which travels upward in front of the pylorus, the prepyloric vein of Mayo. The latter vessel usually connects the right gastric and the gastroepiploic veins. The venous loop along the greater curvature lies between the layers of the greater omentum and is made up of the left and the right gastroepiploic veins. The left gastroepiploic vein passes upward and to the left and empties into the splenic vein. The right gastroepiploic vein runs to the right, arches backward at the pylorus and usually enters the superior mesenteric. The left gastric vein (portal system) anastomoses with the lower esophageal vein; the latter in turn anastomoses with the upper esophageal veins which drain through the azygos into the caval venous system. On this way, an important communication is formed between the portal and the caval systems (portacaval anastomosis). The veins at the inferior end of the esophagus may become distended and varicosed in such conditions as cirrhosis of the liver (portal obstruction); their rupture results in severe hematemesis which may be fatal (seeEsophagus).
The lymph drainage of the stomach follows the 3 branches of the celiac axis (hepatic, gastric and splenic). Hence,there are 3 sets of lymph glands and ducts: (1) hepatic, (2) gastric and (3) pancreaticosplenic. The hepatic glands lie in the lesser omentum along the course of the bile ducts; part of them follow the course of the cystic and the hepatic arteries and are known as the cystic (hepatic) glands. They receive lymph from the liver and the gallbladder. Since this set of glands follows the course of the hepatic artery or its branches, they give rise to a group of glands (subpyloric) which are located on the head of the pancreas and in the angle between the first and the second parts of the duodenum. They receive lymph from the right two thirds of the greater curvature of the stomach; this lymph travels via the inferior gastric glands. Therefore, the hepatic group of glands has 3 separate sets associated with it: a hepatic proper, following the duct; a cystic, following the cystic artery; and a subpyloric, following the gastroduodenal artery. Gastric Glands. The second group of glands is the gastric. It is divided into superior and inferior subgroups. The superior glands follow the course of the left gastric artery along the lesser curvature of the stomach and between the layers of the lesser omentum. The inferior glands follow the right gastroepiploic vessels between the layers of the greater omentum; they are found mainly along the pyloric half of the greater curvature. Pancreaticolienal Glands. The third group is the pancreaticolienal (splenic set). These follow the course of the splenic artery along the upper border of the pancreas. Some are found in the gastrosplenic ligament in relation to the short gastric branches of the splenic artery. Preaortic {Celiac) Glands. The efferent lymphatics from all of these glands pass to glands which surround the celiac axis in front of the aorta; these are known as the celiac group or preaortic glands. The lymph drainage of the stomach can be represented diagrammatically in the following way: the stomach is divided by an imaginary line in its long axis, two thirds being to the right of this line and one third to the left. A line is now constructed dividing the left third into two at the junction of its upper third and the lower two thirds. In this way 3 areas of lymph drainage are marked out. Area 1 represents that part of the stomach which drains into the superior gastric glands; Area 2 drains into the inferior gastric; and Area 3 drains via the pancreaticolienal glands. The celiac group empties into the receptaculum chyli after receiving lymph from all these areas.
Nerves. The stomach is innervated by both the parasympathetic and the sympathetic nervous systems . The parasympathetic nerve supply is derived from the vagus nerves which originate in the medulla, descend in the carotid sheath and into the thorax. On the posterior surface of the root of each lung each vagus aids in 410 ABDOMEN: Esophagogastrointestinal Tract the formation of the so-called posterior pulmonary plexus, and from these, branches continue to the esophagus and the stomach. The nerves then pass through the esophageal orifice of the diaphragm and reach the respective surfaces of the stomach, where the right vagus is known as the posterior gastric nerve and the left vagus as the anterior; they pass along the lesser curvature of the stomach. Much recent work has been done on the anatomy and the distribution of the vagi. Probably our most reliable information comes from
FIG. Lymphatics of the stomach. (A) The arrows indicate the lymph drainage. (B) Diagram of lymph zones and flow.
FIG. Nerve supply to the stomach.
that in only 3 instances were the nerve arrangements comparable with those described in the textbooks as “normal,” the remaining 10 cadavers showed marked variations. The sympathetic nerve supply to the stomach is derived from the celiac (solar) plexus. This consists of a network of intercommunicating nerve fibers and 2 relatively large flat. ganglia, the celiac ganglia The plexus lies in front of the upper part of the abdominal portion of the aorta around the celiac artery. The right and the left celiac ganglia lie on corresponding crura of the diaphragm, the right being situated behind the inferior vena cava. The fibers to the plexus reach it from the greater and the lesser splanchnic nerves. The greater splanchnic nerve on either side arises from the right sympathetic chain between the 5th and the 10th thoracic ganglia.The lesser splanchnic nerve also arises from the sympathetic chain in the region of the 9th and the 10th thoracic ganglia. The greater splanchnic nerve usually terminates in the upper end of the ganglion; the lesser splanchnic reaches the lower end. The celiac plexus supplies nerves which travel along the branches of the celiac artery; these fibers continue along the subdivisions of the 3 vessels and terminate in the stomach wall. In the gastric wall, a plexus is situated between the muscle layers (myenteric plexus) and another in the submucosa (submucous plexus). They contain both sympathetic and parasympathetic fibers, and from them terminal nerve fibers are supplied to the musculature and the glands of the stomach. The stomach has 4 coats: serous, muscular, submucous and mucous. The serous coat is an investment of peritoneum which completely covers the anterior and the posterior surfaces of the stomach; the only uncovered parts are the greater and the lesser curvatures and a small area to the left of the cardia which is in direct contact with the diaphragm. The muscular coat consists of 3 layers of involuntary muscle: an outer longitudinal, a middle circular and an incomplete inner oblique. The longitudinal muscle is continuous with that of the esophagus; the circular layer becomes thickest in the region of the pylorus and forms the pyloric sphincter. In infants, excessive thickening of this circular layer at the pylorus may give rise to the condition known as congenital pyloric stenosis. The submucosa consists of an abundant, loosely arranged connective tissue layer which contains vessels of considerable size. The toughness of this layer explains its ability to hold sutures. The mucosa is freely movable upon its underlying lax submucosa and, in the undistended state, presents numerous folds giving it a rugose appearance. These folds are arranged chiefly in longitudinal directions.
ATTACHMENTS OF THE STOMACH (OMENTA)
Peritoneal folds attach the stomach to the liver, the transverse colon, the spleen, the biliary ducts, the pancreas and the diaphragm. These folds are indicated by such
names as omenta or gastric ligaments. Omenta are defined as compound peritoneal folds which pass from the stomach to other intra-abdominal organs. These attachments are found only along the curvatures of the stomach. The 2 gastric surfaces—the anterior belonging to the general peritoneal cavity and the posterior belonging to the lesser cavity (omental bursa)—are free and unattached. All omenta and gastric ligaments of the adult stomach originate from the midline mesenteries of embryonic life, and the only way to gain a clear picture of these connections is through a visualization of the succeeding steps in gastric development. The lesser omentum is a wide fold of peritoneum which is hidden by the left lobe of the liver. It is attached to the first inch of duodenum, the lesser curvature of the stomach, the diaphragm for Vi inch between the esophagus and the upper end of the fissure for the ligamentum venosum, the bottom of that fissure and to the lips and the right end of the porta hepatis. Its right border is a free edge at which the 2 layers are continuous with each other. It forms the anterior boundary of the opening (foramen of Winslow) into the lesser sac which separates it from the inferior vena cava. Between its layers and at its right border are the common duct, the portal vein and the hepatic artery; the right and the left gastric arteries are found along the lesser curvature. The greater omentum is formed by the elongation of the primitive dorsal mesogastrium which does not cease growing with the completion of gastric rotation but continues until a broad sheet of peritoneum (floor of omental bursa) hangs down from the greater curvature of the stomach, ventral to the coils of small intestine. After passing downward and being reflected upward, it again reaches the dorsal wall of the abdomen at a point slightly above the line of attachment of the transverse mesocolon. It is thereby brought into contact with the upper layer of the transverse mesocolon, with which it ultimately fuses. This brings the floor of the omental burst into union with the transverse mesocolon. The dorsal mesogastrium and the transverse mesocolon fuse to form a common supporting membrane; the layers composing the dependent part of the bursa fuse with each other to obliterate the distal part of the lumen of the bursa. Fat is laid down in this omental apron which provides an insulating layer for the protection of the abdominal viscera. The reflections of the gastric and the omental surfaces of the peritoneum as encountered by the surgeon can be traced easily both with regard to the greater and the lesser peritoneal cavities. Beginning at the porta hepatis, a peritoneal surface extends downward as the anterior leaf of the gastrohepatic (lesser) omentum, passes over the ventral surface of the stomach and then downward as the anterior leaf of greater omentum; it then turns back and upward as the posterior leaf of the greater omentum until the transverse colon is reached. Starting at the porta hepatis again, another peritoneal surface, the dorsal leaf of lesser omentum passes downward, covers the dorsal gastric wall and continues downward from the greater curvature of the stomach; it turns back and upward to the transverse colon as the innermost leaf of the greater omentum. It then passes over the anterior and upper walls of the transverse colon and backward to the posterior parietes as the uppermost layer of the transverse mesocolon. When illustrations of the ascending double layer are studied in the adult, the 2 layers seem to diverge and enclose the transverse colon and continue as the mesocolon. However, this is a wrong impression, since the ascending double layer in the fetus passes up in front of the transverse colon to the posterior wall and to the lower border of the pancreas. On gaining the latter, the anterior or inner serous layer of ascending omentum passes in front of the pancreas as the posterior wall of the omental bursa and then continues over the undersurface of the liver to its starting point. The outer or posterior serous layer of ascending omentum passes behind the pancreas to reach the body wall; it is reflected from this to become continuous with the upper layer of the transverse mesocolon. The original fetal relations become the surgeon’s cleavage planes, which detach the greater omentum from the transverse colon and its mesentery. These peritoneal reflections are related to the wall of the omental bursa in the following way: the pouch extends behind and below the liver and the stomach, above the transverse mesocolon, within the greater omentum (wheot fused) and behind the lesser omentum.
SURGICAL CONSIDERATIONS
GASTROJEJUNOSTOMY Gastrojejunostomy is indicated in the patient who has a pyloric obstruction and low gastric acidity. It is used also as a palliative measure to provide relief for an obstructed pylorus (inoperable carcinoma) or as a preliminary procedure for future surgery. The operation may be done anterior or posterior to the transverse colon.
A posterior gastrojejunostomy is accomplished by passing the posterior wall of the stomach through a rent in the transverse mesocolon and performing an anastomosis between the stomach and a proximal loop of jejunum. The gastric site for the stoma should be placed at the most available and dependent part near the greater curvature and in line with the esophagus. The details and the structural orientation may be found in the description of gastric resection which follows. Following the anastomosis, the rent in the transverse mesocolon is
FIG. Attachments of the stomach (omenta). (A) The early development of the
greater omentum from the primitive dorsal mesogastrium. (B) Later development, showing beginning fusion of dorsal mesogastrium and transverse mesocolon. (C) Adult lesser and greater omenta. The arrow indicates the foramen of Winslow.
sutured to the posterior wall of the stomach to prevent internal herniation. Anterior gastrojejunostomy is preferred by many surgeons; it is technically simpler, does not endanger the middle colic artery and does away with many of the hazards if reoperation becomes necessary. The anastomosis is placed on the anterior surface of the stomach and anterior to the transverse colon. In an anterior gastrojejunostomy it is preferable to suture the greater curvature to the proximal end of the jejunum.
GASTRECTOMY Subtotal gastrectomy is done for carcinoma of the stomach and for peptic ulcer. It is difficult to standardize such a procedure, since every clinic has a technic of its own; however, a standardized subtotal gastrectomy utilizing an end-to-side antecolic anastomosis will be described here. Many men’s names and modifications are associated with gastric operations, but space does not permit a review of such procedures; these can be found in any standard surgical text.
FIG. Posterior gastrojejunostomy. (A) An incision has been made in the transverse mesocolon to the left of the middle colic artery. (B) The posterior wall of the stomach is delivered through the rent in the mesocolon. (C) The lesser curvature is approximated to the proximal jejunum and the greater curvature to the distal end of the jejunal loop. (D) The anastomosis. (E) The stomach is sutured to the esocolon. (F) The completed anastomosis.
The incision is usually one of the upper rectus incisions, either placed to the right or the left of the midline, depending on the surgeon’s preference and the site of the lesion. Operability must be determined first. This can be done by opening the hepatogastric part of the lesser omentum and placing a finger into the lesser peritoneal cavity. The index finger of the left hand serves admirably for this purpose; it makes its exit through an avascular point in the gastrocolic part of the greater omentum. A strip of gauze replaces the finger and is used for traction. This too greatly simplifies exposure of the duodenum and also protects the transverse mesocolon with its middle colic artery which will lie behind the gauze traction tape. Mobilization of the greater curvature is accomplished next; it extends to the “avascular triangle” on the left, and an inch distal to the pylorus on the right. After freeing the greater curvature of its vascular attachments and ligating the left and the right gastro-epiploic arteries, the lesser curvature is mobilized. Mobilization of the lesser curvature already has been partially accomplished by the opening made in the hepatogastric part of the lesser omentum; this is continued by cutting and ligating the right gastric artery. After mobilization of the curvatures, upward traction is maintained on the gauze tape so that the stomach may be separated from its attachments posteriorly to the pancreas (pancreaticogastric folds). In patients who have an adherent ulcer which is situated in the duodenum, it is safer to expose and thus protect the common duct. Division of the duodenum is accomplished next; the distal end is closed. Ligation of the left gastric artery is simpler and safer after the stomach has been severed from its duodenal attachment. Then the stomach can be retracted to the patient’s left side; this enables the surgeon to visualize the left gastric artery as it approaches the lesser curvature posteriorly. Location of the ligament of Treitz is accomplished by making upward traction on the transverse colon, thus stretching its mesocolon; the duodenojejunal angle and the ligament of Treitz will be found immediately to the left of the midline. To perform the antecolic operation, a long jejunal loop is required; this usually measures from 10 to
TRANSABDOMINAL VAGUS NERVE SECTION (VAGOTOMY). The abdominal approach to the gastric nerves (vagi) allows exploration of the abdominal contents and the lesion; it also facilitates the performance of a gastro-enterostomy if pyloric obstruction is present or is likely to occur. A long incision is necessary for proper exposure. A left muscle-splitting rectus incision which commences in the angle between the xiphoid and the left costal cartilage and extends 1 or
FIG. Subtotal gastrectomy (Continued): (E) locating the ligament of Treitz and the duodenojejunal junction; (F) the jejunum has been brought over the front of the ransverse colon and approximated to the posterior wall of the stomach; (G) the anastomosis; (H) the completed antecolic, end-to-side gastrojejunostomy following resection of the involved stomach.
cords which can be differentiated readily from the more yielding muscle of the esophagus. The left (anterior) vagus has a tendency to hug the esophagus, but the right (posterior) vagus travels a slight distance away from it. By finger dissection the fibers are assembled into 2 main trunks comprising the right and the left vagi; these are ligated and divided. The position of the right and the left trunks below the esophageal hiatus is found to be
remarkably constant; however, many times these nerves are numerous and communicating, and their distribution does not follow a uniform pattern. At the conclusion of the operation, the left lobe of the liver is permitted to fall into place; it has been found unnecessary to resuture the severed left triangular ligament. CARCINOMA OF THE LOWER THIRD OF THE ESOPHAGUS AND THE CARDIAC END OF THE STOMACH
Most lesions involving the lower part of the esophagus and the cardiac end of the stomach can be removed through a combined thoracico-abdominal approach. The incision affords an excellent exposure of the upper abdomen and the thoracic cavity, thus enabling more extensive resections. Humphreys, Garlock, Adams and Phemister, Marshall,Churchill and Sweet—all have applied some form of this approach for such lesions.A left upper rectus incision is made; this extends from or below the umbilicus to the left costal arch. The peritoneal cavity is entered, and a thorough exploration is carried out to determine the extent of the growth, fixation to vital structures and the presence or the absence of metastases (liver, peripancreatic, pelvic and diaphragmatic). Should the tumor prove to be operable, the incision is extended over the costal arch and then upward and outward into the 7th intercostals interspace. The costal arch is divided, and the pleural cavity is entered. The intercostals muscles and the pleura are incised well past the inferior angle of the scapula, and the left leaf of the diaphragm is severed. The diaphragm is divided radially from the esophageal hiatus to its peripheral attachment. Large phrenic vessels are encountered; these should be properly isolated, divided and tied. The inferior pulmonary ligament is severed; this exposes an esophageal triangle which is
bounded in front by the heart, behind by the descending aorta and below by the diaphragm. In this triangle the esophagus can be identified easily. The technic for the resection and the anastomosis is essentially the same as that described under lesions of the midthoracic esophagus. The diaphragm is repaired, and the now somewhat enlarged esophageal hiatus is sutured to the stomach. The pleura, the intercostals muscles and the overlying soft tissues are approximated, and the abdominal incision is closed in layers.
CLOSURE OF A PERFORATED PEPTIC ULCER
Most perforations of a peptic ulcer occurat the so-called “dollar-area.” This circular area, about the size of a silver dollar, is bisected by the pylorus. Normally, the right lobe of the liver covers this region and attempts to seal the perforation. Therefore, to locate most perforated peptic ulcers, the right lobe of the liver should be retracted upward, and the stomach should be pulled gently in a downward direction and to the left. If the perforation is not found with this maneuver, then the lesser and the greater curvatures should be examined; still failing to find the ulcer, the gastrocolic ligament must be severed and the posterior wall of the stomach inspected. Many methods of repair have been advocated; these vary from a simple graft of omentum placed over the perforation to excision and closure.
Liver (Hepar)
EMBRYOLOGY The hepatic diverticulum is the primordial outgrowth of cells destined to form the secretory tubules of the liver, its duct system and the gallbladder. It arises ventrally during the 4th week from the entodermal lining of the gut, and when it is first recognizable, it lies just caudad to the heart. A maze of anastomosing and branching cell cords grows ventrad and cephalad. The distal portions of these cords give rise to the secretory tubules of the liver, and their proximal portions form
FIG. The embryology of the liver.
the hepatic ducts. The growing hepatic tubules push between the 2 layers of splanchnic mesoderm which form the ventral mesentery and spread these 2 layers apart. The investing mesodermal layers form the fibrous connective tissue capsule of the liver and the interstitial connective tissue of the liver lobules. At about the 3rd week the vitelline veins of the yolk sac pass through the septum transversum to the sinus venosus. The vitelline veins divide and intermingle with the liver cords to form an irregular mass of sinusoids. The terminal ends of these veins project out of the liver and enter the sinus venosus. A series of anastomoses take place between the vitelline veins. In the liver the 2 veins communicate ventral to the duodenum. Near the liver there is another anastomosis which is located dorsal to the duodenum, and below this there is a third which is again ventral to the duodenum. As a result of partial atrophy of the vitelline veins an “S”-shaped vessel results which passes around the gut and toward the liver. By this time the yolk sac and part of the vitelline veins atrophy. The remainder of these veins persists as the superior mesenteric vein; with the splenic vein it enters into one of the ventral anastomoses, thus forming the portal vein. The right vitelline vein distal to the anastomosis disappears. The umbilical veins on their way to the sinus venosus contact the growing right and left lobes of the liver. The liver taps the blood from these veins which now mixes freely with the blood from the vitelline veins of the sinusoids. As a result of this the original connections of the umbilical veins to the sinus venosus atrophy. By the 6th week the right umbilical vein becomes smaller and gradually disappears. Therefore, placental blood is drained by only the left umbilical vein into the liver. Simultaneously, the opening of the sinus venosus is shifted to the right side. The large amount of blood entering the liver via the right umbilical vein takes a diagonal passage across the sinusoids and toward the right side of the sinus venosus. This new channel is known as the ductus venosus. The part of the right vitelline vein which is situated between the liver and the sinus venosus becomes the main passageway of the veins entering the heart. It forms the terminal part of the inferior vena cava. The corresponding proximal part of the left vitelline vein disappears. After birth, the umbilical vein obliterates, and its remnant, the ligamentum teres, remains as a fibrous cord between the umbilicus and the liver. The ductus venosus becomes the solid ligamentum venosum.
THE LIVER PROPER The liver is the largest gland in the body; it is extremely vascular and has many functions to perform. It receives its arterial blood supply from the hepatic artery, and the portal vein conveys blood to it from the intestinal tract. The blood of the liver is drained by the hepatic veins, which open into the inferior vena cava. This organ resembles the shape of a pyramid, the base being to the fight and the apex to the left; the sides of the pyramid are formed by the superior, the inferior, the anterior and the posterior surfaces. In the adult it constitutes approximately l/50th of the body weight; it occupies the uppermost part of the abdomen, chiefly on the right side. The organ is in close relation with the diaphragm and is covered by the ribs, which afford it some protection. At birth the liver is relatively larger. This is especially true of the left lobe; the prominent bulging of an infant’s abdomen is mainly due to the large size of the gland. The falciform ligament of the liver is a wide fold of peritoneum which lies obliquely between the liver and the anterior abdominal wall. The right surface of this ligament is in close contact with the abdominal wall, and the left surface is in contact with the liver. The ligament has 3 borders: an upper border which is attached to the diaphragm and to the anterior abdominal wall as far as the umbilicus; the second border is attached to the upper and the anterior surfaces of the liver, dividing it into right and left lobes; the third border is a free edge where the 2 layers of the ligament become continuous with each other. The round ligament (ligamentum teres) passes in this free edge. If the left lobe of the liver is pulled away from the diaphragm, a fold of peritoneum,
FIG. The so-called “true” lobation of the liver. The heavy line divides the liver into right and left lobes. This division corresponds to the distribution of the right and the left hepatic ducts, the right and the left hepatic arteries and the right and the left branches of the portal vein. It should be noted that the caudate lobe belongs to both right and left liver lobes.
the left triangular ligament, is placed on the stretch. It connects the left hepatic lobe to the diaphragm and presents 3 borders. One border is attached to the back of the upper surface of the left lobe; the second is attached to the central tendon of the diaphragm and the third is a free edge which is directed toward the left where the 2 layers of the ligament are continuous with each other. If the fingers of the right hand are passed backward over the top of the right lobe, they are stopped by a layer of peritoneum which is known as the upper layer of the triangular {coronary) ligament. This is reflected from the back of the right lobe onto the diaphragm. If the fingers of the left hand are passed upward behind the right part of the right lobe and pressed backward, they will be stopped by the lower layer of the triangular {coronary) ligament. The lower layer is reflected from the inferior surface of the liver onto the right kidney, the adrenal gland and the inferior vena cava; it also is referred to as the hepatorenal ligament. Below this ligament is a peritoneal space known as the hepatorenal pouch (Morison’s). The upper and the lower layers of the coronary ligament approximate each other at the right extremity of the liver, and where they fuse they form the right triangular ligament. This ligament is not as well marked as the left, because its 2 layers diverge so rapidly. Between the 2 layers of the coronary ligament there is a fairly large triangular area of liver which is devoid of peritoneum and is known as the bare area; it is attached directly to the diaphragm by areolar tissue. The apex of this bare triangular area corresponds to the meeting point of the 2 layers of the coronary ligament on the right where they form the right triangular ligament. The base of the triangle is formed by the fossa for the inferior vena cava. The bare area is in contact with the inferior vena cava, the upper part of the right suprarenal gland and the diaphragm. It is connected to the liver by connective tissue in which are found the veins of Retzius, which form a portasystemic anastomosis. The student’s “crutch,” the time-honored letter “H,” is formed by structures which lie on the inferior surface of the liver. The left limb of the letter “H” divides this surface into right and left lobes. It contains embryonic structures, namely, the fissure for the ligamentum teres (left umbilical vein) in front and the fissure for the ductus venosus behind. Fetal blood is returned from the placenta to the fetus by means of the umbilical vein, which enters the abdomen at the umbilicus, passes upward along the free margin of the falciform ligament to the undersurface of the liver. At the transverse fissure of the liver (porta hepatis) it divides into 2 branches; one of these joins the portal vein and enters the right lobe, the other joins the ductus venosus, thereby shortcircuiting the blood to-the inferior vena cava. Therefore, since the umbilical vein and the ductus venosus were continuous with each other in fetal life, it is quite natural that their adult landmarks (ligamentum teres and ligamentum venosum) should also be continuous, thereby forming the left limb of the “H.” The right limb of the “H” contains visceral structures, the fossa for the gallbladder in front and the inferior vena cava behind. The transverse part of the “H” is formed by the porta hepatis (the transverse fissure) and this contains, from before backward, the hepatic duct, the hepatic artery and branches of the portal vein. The porta is deep and wide and is about
LOBES AND SURFACES Lobes. It has long been taught that the
liver consists of 2 lobes—a larger right and a smaller left lobe. The proportion between the 2 is as 6 is to 1. They are divided by the fissure for the ligamentum venosum on the posterior surface, the fissure for the ligamentum teres on the inferior surface and the attachment of the falciform ligament on the superior and the anterior surfaces. Two circumscribed areas which are found over the medial part of the right lobe are also referred to as “lobes”; they are the quadrate lobe on the inferior surface, situated between the gallbladder and the fissure for the ligamentum teres, and the caudate lobe on the posterior surface, situated between the inferior vena cava and the fissure for the ligamentum venosum. McNee and others believe that the true anatomic and physiologic division of the liverinto right and left lobes is by a plane that passes through the fossa of the gallbladder and the fossa of the vena cava. The two parts thus separated are approximately equal in size, with each lobe having its own arterial supply, portal supply and biliary drainage. Therefore, we must differentiate between an anatomic (surgical) division of the lobes and a true (functional) division. Bilaterality of the liver has been studied for many years. Healey and Schroy have reported on an analysis of the prevailing patterns of branchings of the biliary ducts. They have also included in their study the major variations of such branchings. Their description of a prevailing pattern of bile ducts is presented in Figures. It should be noted that such branching is associated with divisions of the liver into various segments. The liver is divided into a right and a left lobe by a lobar fissure that is roughly in line with the gallbladder bed and the inferior vena cava on the visceral surface. The right lobe of the liver is divided by the right segmental fissure into anterior and posterior segments. The left lobe is divided by the left
segmental fissure (fossa for the ligamentum venosum) into medial and lateral segments. In turn, each segment is divided according to its biliary drainage into superior and inferior areas. It is the opinion of these authors that the quadrate lobe should be regarded as pertaining to liver tissue that is associated with the medial segment. Intrahepatic anatomy of the bile ducts becomes increasingly important surgically, since various methods are now described for corrective procedures on previously involved or injured common ducts. This is true particularly in intrahepatic cholangiojejunostomy with partial hepatectomy (Longmire). Partial hepatectomies arealso being performed for tumors of the liver. Surfaces. The base of the pyramidalshaped liver is the right lateral surface; it is somewhat quadrilateral and convex. It is related to the diaphragm opposite the 7th to the 11th ribs in the midaxillary line. The pleura and the right lung are important relations to this surface; they are separated by the diaphragm. In the midaxillary line the pleura overlaps the liver as low as the 10th rib and the lung to the 8th. The 12th rib, asa rule, does not reach sufficiently far forward to come into relationship to this hepatic surface. Therefore, a puncture wound over the lower part of the right side of the thorax may pass through the pleura, the lung, the diaphragm, the peritoneum and the liver. The anterior surface of the liver is of considerable clinical importance, since it is the surface which is most readily accessible for examination as far as the 10th costal cartilage on the right side. The median portion, which lies against the anterior abdominal wall, is palpated easily and thus yields valuable information. If inspiration is forced, almost the entire inferior border of the liver can be felt. The superior surface is related to the diaphragm, which separates it from the 2 pleural sacs and the pericardium. On the right side it rises into a convexity that reaches almost to the level of the right nipple. On the left, the surface ends as a thin edge which is opposite the 5th rib in a line dropped from the left nipple. The posterior surface cannot be seen until the liver has been removed from the body.
FIG. Two views of the segmental area of the liver.
On the left this surface is covered with peritoneum of the greater sac, and a groove made by the esophagus is formed here. In the median plane is the caudate lobe, which is covered with peritoneum of the lesser sac. This lobe lies between the fossa for the vena cava and the fossa for the ductus venosus. To the right of this the bare area is found. The inferior vena cava occupies the leftmost portion of the area, and the kidney and the adrenal gland encroach upon it from below. The inferior surface also has been called the visceral surface of the liver. It faces downward, to the left and backward. It is covered with the peritoneum of the greater sac and everywhere shows the imprints
FIG. Ligaments of the liver. The liver has been displaced to the right and out of the peritoneal cavity so that its Iigamentous attachments may be seen. Therefore, this illustration shows the posterior aspect of the liver and the anterior aspect of the posterior abdominal wall to which the liver is normally attached.
FIG. Diaphragmatic attachments of the liver; (A) relationships of heart and lungs; (B) seen from below the diaphragm, with the liver removed.
of viscera with which it is in contact. It is only distinctly separated from the inferior surface, and the “H” which has been described occupies this surface. The part of this surface which belongs to the left lobe isrelated to the stomach and to the lesser omentum. The gastric impression appears as a wide, shallow, concave area to the left. The omental part is a bulging prominence to the right and behind; it is called the tuber omentale. The quadrate lobe lies between the fissure for the ligamentum teres and the fossa for the gallbladder. This lobe is related to the pyloric part of the stomach and the first part of the duodenum below, and to the right part of the lesser omentum above. It is the quadrate lobe which attempts to seal over perforated peptic ulcers, the vast majority of which occur in this portion of the stomach or in the duodenum. The gallbladder lies in front of the first and the second parts of the duodenum, but the latter extends beyond it and is in relation to the adjoining part of the right lobe. Directly to the right of the duodenal area the right colic flexure leaves its imprint, and behind this the undersurface of the right lobe is related to the right kidney, which leaves its renal impression. The liver is completely covered with peritoneum except in 3 locations, namely, the bare area, the groove for the inferior vena cava and the gallbladder fossa. The lesser omentum is attached to the margins of the porta hepatis and around its right extremity; its 2 layers are continued from the left extremity of the porta hepatis to the fissure for the ligamentum venosum. At the upper end of this fissure these 2 layers separate. The ligaments mentioned in connection with the liver should not be regarded as supporting the entire weight of the organ, since it, like other abdominal and pelvic organs, is kept in place by intra-abdominal pressure which is attributed mainly to the tonus of the muscles of the anterior and the lateral abdominal walls. Therefore, it is of little or no consequence when one of the so-called “supporting” ligaments of the liver is severed during surgical procedures, since the liver will not become ptotic.
FIG. Diagrammatic representation of fetal circulation.
VESSELS, NERVES AND LYMPHATICS ARTERIES. The liver has 3 vessels associated with it: the hepatic artery, the portal vein and the hepatic veins. The hepatic artery, one of the trifurcating branches of the celiac axis, supplies arterial blood to the substance of the liver. Daseler, Anson et al. reported on investigations made in 500 laboratory specimens. They observed that the common hepatic artery arose as a branch of the celiac axis in 416 of the 500 (83.20%). This vessel was absent in 61 cases (12.20%). When the common hepatic artery was absent, the right and the left hepatic lobes derived their arterial supply from separate branches. These anatomists found that in 358 of 439 cases studies (81.54%) the common hepatic artery was a rather long trunk which divided into its hepatic branches within
FIG. The portal vein and the portal system.
supply to the liver were the same. The hepatic artery varied in the origin, the caliber, number and the distribution of its main branches. The typical common hepatic artery divides into a right, a middle (to the quadrate lobe) and a left branch.To shut off completely the arterial blood supply to the liver would be fatal, but a collateral anastomosis exists. In recent years opinions have been divided as to whether or not necrosis will result in man from ligation of a common, a right or a left hepatic artery. Viability of the liver may be explained by the following: (1) If the common hepatic artery is ligated, hepatic circulation is maintained in a ratio of 1 to 8 because the right artery may arise from the superior mesenteric artery. (2) If the right or the left hepatic artery is ligated, the corresponding lobe does not of necessity necrose. This is explained by the fact that the larger branches of the right and the left hepatic arteries (precapillaries) anastomose with each other in the fissure of the liver. (3) If the hepatic artery is obstructed gradually on the aortic side of the right gastric artery, circulation may be maintained by the anastomosis of the right and the left gastric arteries. Hence, it must be accepted that the effects of ligation of the so-called “normal” hepatic artery would differ at various levels.Veins. The portal vein also brings a great quantity of blood to the liver. This vessel is formed between the head and the neck of the pancreas by the union of the splenic, the superior mesenteric and the inferior mesenteric veins. It forms a rather thick vessel, which measures about 7 1/2 cm. in length. At the porta hepatis it divides into right and left branches. If the portal vein is obstructed by either intrahepatic or extrahepatic causes, the portal blood is shunted to the systemic veins where the 2 systems meet. This collateral circulation has been referred to as the accessory portal system.
FIG. Ligation of the common hepatic artery at A would spare the entire collateral circulation; it should be noted that in this instance the gastroduodenal and the right gastric arteries are distal to the point of ligation. At B the ligation is placed distal to the gastroduodenal but proximal to the right gastric artery; this could markedly reduce the collateral circulation. A ligature at C or beyond this point abolishes the collateral channels, thus depriving the liver of arterial blood. Accessory vessels may be present, and some authors believe that these could prevent necrosis.
FIG. The 6 subphrenic spaces: (A) the 3 suprahepatic spaces; (B) the 3 infrahepatic spaces.
The hepatic veins carry blood from the liver to the inferior vena cava. Some of these veins are small and open into the vena cava at various points; however, the chief hepatic veins are a left and a right, coming respectively from the right and the left liver lobes. They enter the inferior vena cava immediately before it leaves the liver. Nerves. The nerves of the liver are derived from the left vagus and the sympathetic. They enter at the porta hepatis and accompany the vessels and the ducts to the interlobular spaces. Lymphatics. The lymph vessels of the liver terminate largely in a small group of lymph glands in and around the porta hepatis. The efferent vessels from these glands pass to the celiac lymph glands. Some of the superficial lymph vessels in the anterior surface of the liver pass to the diaphragm in the falciform ligament and finally reach the mediastinal glands. There is another group which accompanies the inferior vena cava into the thorax and ends in a few small glands which are related to the intrathoracic part of the vessel.
SURFACE ANATOMY The limits of the liver are determined by palpation and percussion. Only an approximation of the size of the gland can be obtained; the exact location of these limits is difficult to obtain because the lower edge of the lung overlaps the liver above, and the lower edge of the liver overlaps the stomach and the intestine below. The upper limit of the right lobe (highest point of the liver) lies beneath the right dome of the diaphragm; it is on a level with the upper margin of the 5th rib about
PRACTICAL AND SURGICAL CONSIDERATIONS
THE 6 SUBPHRENIC SPACES
The one large subphrenic area is divided into 6 subphrenic spaces. The “subphrenic space” is a region situated between the diaphragm above and the transverse colon and its mesocolon below. The liver divides this space into suprahepatic and infrahepatic spaces. The suprahepatic space is bounded above by the diaphragm and below by the superior surface of the liver; the infrahepatic space is bounded above by the inferior surface of the liver and below by the transverse colon and its mesocolon. Suprahepatic Spaces. The suprahepatic space is divided into 3 smaller suprahepatic (subphrenic) spaces in the following way: the suprahepatic area is divided into right and left portions by the falciform ligament, which extends between the superior surface of the liver and the diaphragm. From the back of the right lobe of the liver and running upward to be reflected onto the diaphragm, is the upper layer of the coronary ligament. A space is now formed which lies above the liver, to the right of the falciform ligament and in front of the upper layer of the coronary ligament. Therefore this space is called the right superior anterior subphrenic space. It is bounded above by the diaphragm, below by the superior border of the liver, behind by the upper layer of the coronary ligament and medially by the right surface of the falciform ligament. The lower layer of the coronary ligament on the right forms the roof of a space which is limited by the liver in front and the posterior parietal peritoneum behind. This is smaller than the anterior space just described; since it still is associated with the superior surface of the liver and since it lies to the right of the falciform ligament but behind the lower layer of the coronary ligament, it is called the right superior posterior subphrenic space. To the left of the falciform ligament but still in the suprahepatic area, the left triangular (coronary) ligament courses along the posterior border of the left lobe of the liver and separates the superior surface from the inferior surface of the liver. In this respect it differs from the ligament on the right, which has 2 diverging layers, thus dividing the superior surface on the right into anterior and posterior spaces. Since the layers of the left ligament do not diverge, and since they run directly at the junction of the superior and the inferior borders, the left suprahepatic space constitutes only one space and is not divided into two. It is called the left superior subphrenic space and is bounded by the diaphragm above, the superior surface of the left lobe of the liver below and the left side of the falciform ligament medially. Infrahepatic Spaces. The infrahepatic area also is divided into 3 subphrenic spaces. In addition, this area is divided into right and left sides by the round ligament and the ligament of the ductus venosus. To the right of these structures is a large space known as the right inferior subphrenic space. It is bounded above by the inferior surface of the liver and below by the transverse mesocolon and the colon; medially, it extends to the round ligament. To the left are 2 spaces separated from each other by the stomach and the lesser omentum. The space anterior to the stomach is known as the left anterior inferior subphrenic space, and the space posterior to the stomach is known as the left inferior posterior subphrenic space. The left anterior inferior space also has been referred to as the perigastric space; in this space a perigastric abscess may form following the perforation of a peptic ulcer. The right inferior space is bounded above by the inferior surface of the liver, below by the transverse colon and the mesocolon and anteriorly by the anterior abdominal wall. The left inferior posterior subphrenic space is better known as the lesser peritoneal cavity. It is bounded above by the inferior surface of the liver; below, by the transverse mesocolon; anteriorly, by the stomach and the lesser omentum; and, posteriorly, by the posterior parietal peritoneum of the lesser sac. The bare area, which is really the space within the confines of the coronary ligament, has not been included as one of the 6 subphrenic spaces but is considered as an extraperitoneal space. The space most frequently involved in infection and abscess formation is the right posterior superior space. The reason for this is that the most frequent causes of peritoneal contamination are on the right side (suppurative appendicitis, cholecystitis or perforated peptic ulcer). The right posterior superior space is the earliest space involved because inflammatory exudates travels upward from the right iliac fossa and along the paracolic gutter.
DRAINAGE OF SUBPHRENIC ABSCESSES
Alton Ochsner and Amos Graves have done much to standardize the treatment of subphrenic abscesses. They conclude that adequate drainage of such an abscess should consist of early and proper evacuation in such a way that contamination of the peritoneal and the pleural cavities is avoided. The various spaces are approached through different routes. The right superior posterior space, which is the most frequent to be involved, is drained through a “retroperitoneal operation.” The right inferior space frequently is associated with it and may be drained simultaneously through the same incision. This approach does not enter the pleural or the peritoneal cavities. The technic is as follows. The patient is placed upon the unaffected side and on a kidney rest. The incision is made directly over the 12th rib, which is resected subperiosteally; the erector spinae muscle mass is retracted medially. A transverse incision is made at right angles to the spine, which passes across the rib bed at the level of the spinous process of the 1st lumbar vertebra. The incision through the 12th rib bed is made transversely and not parallel with the skin incision; only in this way can one be sure that the pleural cavity will not be entered. The costophrenic angle of the pleura has not been found to pass caudally as far as the
FIG. Portacaval shunts. (A) This depicts an end-to-side anastomosis between the portal vein and the inferior vena cava. The remaining cut end of the portal vein has been ligated close to the liver. (B) The end of the splenic vein has been anastomosed to the side of the left renal vein. The spleen has been removed.
spinous process of the 1st lumbar vertebra. The transverse incision passes through the bed of the 12th rib and the attachment of the diaphragm, the latter appearing usually as a few muscle fibers. Directly beneath this, the renal fascia is identified; it is continuous above and anteriorly with the posterior parietal peritoneum. The peritoneum is separated from the undersurface of the diaphragm, and the right superior posterior subphrenic space is entered. The abscess cavity is entered and drained. Abscesses which involve the right superior anterior, the right inferior, the left anterior inferior and the left superior spaces can be drained extraperitoneally through an anterior approach. If the retroperitoneal approach can be employed for the right inferior space, this is preferable. However, in those cases which require anterior
FIG. The author’s modification of the Longmire operation for irreparable damage to the common and/or the hepatic ducts. It should be noted that 2 anastomoses are performed. In addition to the usual catheter the author has added a T-tube.
approaches (right superior anterior and left superior), one attempts to follow the suggestion of Clairmont and drain these both extraperitoneally and extrapleurally. The incision is made just beneath and parallel with the costal margin through the oblique abdominal muscles and the transversalis fascia to the peritoneum. The parietal peritoneum is separated from the undersurface of the diaphragm, and the peritoneum is mobilized upward until the abscess is reached. The cavity is opened extraperitoneally and drained.
PORTACAVAL SHUNTS Recent favorable reports by Whipple, Blakemore, Linton and others have stimulated interest in various types of portacaval shunts. These procedures are being done at present for cases of portal hypertension which have tendencies toward esophagogastrointestinal bleeding. Various types of shunts have been used, the most common of which is an anastomosis between the portal vein and the inferior vena cava. This anastomosis has been done in the form of an end-to-side portacaval shunt; this is done wholly as an abdominal procedure and requires the dissection and the isolation of the structures in the hepatoduodenal part of the lesser omentum (portal vein, common duct and hepatic artery). More recently, Blakemore has described a right thoracicoabdominal approach which provides excellent exposure of both the inferior vena cava and the portal vein. With this incision, a lateral anastomosis between the vessels is possible, and the dissection of the common duct and the hepatic artery is unnecessary. Other types of shunts which have been used are the divided superior mesenteric vein to the side of the inferior vena cava distal to the renal veins, the proximal end of the divided inferior mesenteric vein to the side of the left ovarian vein and end-to-side splenorenal anastomosis. Rienhoff has advocated hepatic artery ligation for portal hypertension.
LIVER RESECTION Resective lesions have increased during recent years, particularly neoplastic and traumatic lesions of the liver. Major hepatic resections with lowered morbidity and mortality are being accomplished by strict adherence to surgical principles and anatomic knowledge. The works of Healey and Schroy and of Goldsmith and Woodburne can be referred to for their views regarding “planes” of resection. The caudate lobe is usually treated as an area unto itself. The Longmire operation (intrahepatic cholangiojejunostomy) and its modifications should be in the armamentarium of every surgeon interested in biliary tract surgery. This may be a last resort whereby a life can be saved following injury to and reparative processes of the common duct.
Gallbladder and Bile Ducts
EMBRYOLOGY The hepatic diverticulum arises from the foregut, and from it the gallbladder and the extrahepatic biliary ducts develop. At first the gallbladder lies in the ventral mesentery; at the 2nd month it becomes embedded inhepatic tissue; and at a later date it assumes its superficial position. The lumina of the gallbladder and also of the ducts is occluded by an epithelial proliferation during the 2nd month. Occasionally, the bud for the gallbladder divides, giving rise to a double or bifid organ.
ADULT GALLBLADDER AND BILE DUCTS (VESSELS) The gallbladder (vesica fellea) is a pearshaped hollow viscus which is closely connected to the inferior surface of the right lobe of the liver. Usually, it is from 3 to
1 1/2 ounces of bile and forms the right boundary of the quadrate lobe of the liver. The peritoneum which is reflected from its sides attaches it to the liver. It consists of a fundus, a body, an infundibulum and a neck. Fundus. The fundus usually projects beyond the liver and at times may be kinked or notched, forming a so-called Phrygian cap; if this cap is well developed, the fundus becomes fixed and folded. When the fundus protrudes beyond the liver margin it is cov ered on all sides with peritoneum.
FIG. Surface anatomy of the gallbladder. The fundus of the normal gallbladder usually is found in an angle formed by the right rectus muscle and the costal margin.
It is in contact with the anterior abdominal wall opposite the 9th costal cartilage in an angle formed between the right rectus muscle and the costal margin. Body. The body is the main part of the gallbladder; it lies in the fossa on the inferior surface of the liver. It is covered with peritoneum at the side and below, but its superior (anterior) surface is in direct contact with the liver; its inferior (posterior) surface is related to the second part of the duodenum and to the transverse colon. Usually, no peritoneum is found between the posterior part of the body of the gallbladder and the liver; however, occasionally the gallbladder may be loosely attached and mobile by a fold of peritoneum which
surrounds the entire organ and forms a mesentery. Infundibulum. The injundibulum {Hartmann’s pouch) is that part of the organ which is situated between its body and its neck; it appears as an overhanging pouch which runs parallel with the cystic duct and thereby hides it. Hartmann’s pouch is one of the most important surgical guides for proper identification and exposure of the cystic duct. The pouch is bound down toward the first part of the duodenum by the right edge of the lesser omentum, preferably referred to as the cholecystoduodenal ligament. This ligament is also a most important anatomic landmark in surgery; only by serving it can Hartmann’s pouch be mobilized properly and the cystic duct identified clearly. The cholecystoduodenal ligament, which is present in almost all cases as a normal structure, has been referred to erroneously as “adhesions.” Neck. The neck of the gallbladder continues from the upper part of the infundibulum and narrows to become the cystic duct. It is closely applied to the liver and is in relation inferiorly with the end of the first part of the duodenum. M. Lichtenstein is of the opinion that the spiral valve of Heister is an infolding of the wall of the cystic duct which is found only in bipeds.
FIG. Possible paths of spontaneous rupture or auto-anastomoses between the gallbladder and the surrounding viscera.
He believes that its function is to maintain the patency of the cystic duct. It is the presence of this valve that makes catheterization or probing of the duct difficult. Since the gallbladder is so closely related to the duodenum, the jejunum, the transverse colon, the liver and the abdominal wall, spontaneous rupture or
FIG. Variations of the cystic duct (
auto-anastomoses between it and these organs might occur Ducts. The cystic duct is usually about
FIG. Types of union of the common bile duct and the pancreatic duct: (A) both ducts open independently into the ampulla; (B) both ducts open independently into the bowel; (C) both ducts join and open into the ampulla by a common channel.
FIG. The so-called “normal” cystic artery and the triangle of Calot. The triangle is formed by the cystic artery (base) and the junction of the cystic and the hepatic ducts (apex).
union of the cystic and the hepatic ducts. It begins near the porta hepatis and descends in the free margin of the lesser omentum; it then continues behind the first part of the duodenum and enters a groove in the back of the head of the pancreas. It passes through the pancreas, downward and slightly to the right, and ends in the second part of the duodenum a little below its middle and on its posteromedial surface. It is convenient to divide the common duct into the following 4 parts, each being related surgically to the duodenum:
1. The supraduodenal portion of the common duct is that part which is situated above the duodenum; it is about
2. The retroduodenal part is situated behind the duodenum, with the right edge of the portal vein behind it and the gastroduodenal artery to its medial or left side. Since the first part of the duodenum is usually quite mobile, this part may be exposed with ease.
3. The infraduodenal part is located below the duodenum. Since the head of the pancreas is in this region, it has also been referred to as the pancreatic portion of the common duct. This part of the duct does not pass between the duodenum and the pancreas but usually forms a groove, or at times a tunnel, in the upper and lateral parts of the posterior surface of the pancreas through which it passes. Because of its intrapancreatic position, this part of the duct is difficult to expose. It is closely related to the right edge of the inferior vena cava, which lies behind it. The portal vein approaches it obliquely from below and from the left, and the gastroduodenal artery is on its left side. This part of the duct is placed in a cage of vessels formed by the vasa recti which arise from the arcades formed by the superior and the inferior pancreaticoduodenal arteries.
4. The intraduodenal portion is that part of the common duct which passes obliquely through the wall of the duodenum and enters it in its second part. This section of the duct is joined on its left side by the main pancreatic duct. A reservoir usually is formed by this junction within the duodenal wall; it is known as the ampulla of Vater. The latter opens into the duodenum on the summit of an elevation known as the duodenal papilla. Various types of union of the pancreatic duct and the common bile duct are possible. Both ducts may open independently into the ampulla, they may open independently into the bowel, or they may even join together and open into the ampulla by a common channel. Therefore, a stone blocking the papilla will not always have the same effect; the effect depends on the type of union which is present.
The intrinsic and proximate blood vessels of the common and the hepatic ducts have been studied and described by Shapiro and Robillard. The important arterial branches to these ducts primarily arise from the cystic and the posterosuperior pancreaticoduodenal arteries, rather than from the hepatic artery, as has been thought previously. Therefore, it is important to do minimal stripping for exposure along the medial side of the duct to reduce the danger of devascularization and ischemic necrosis in common duct surgery. The venous drainage of the extrahepatic biliary passages is upward into the hepatic veins without major anastomoses with the portal system. Cystic Artery. This is one of the most anomalous structures in the body. The socalled “normal” cystic artery is found in about 60 per cent of the cases and arises as a branch of the right hepatic artery. When the artery arises in this manner, a cystic triangle
of Calot is formed; the base of this is the cystic artery; the apex is formed by an angle which results from the junction of the cystic and the hepatic ducts. As a rule, the cystic artery divides into a superficial and a deep branch, the latter being distributed to the medioposterior, nonperitoneal surface of the gallbladder. Daseler, et al. reported on a study of 500 cadavers and have classified the sites of origin of the cystic artery into 12 different types. Duplications and triplications of the vessel have been reported. Since most cases of duct injury are due to hemorrhage from a divided cystic artery or an anomalous arterial branch, the surgeon must acquaint himself with the possible arterial patterns and attempts to identify them. The course of the cystic artery is so variable, and the occurrence of duplicate and triplicate branches so common, that perfect exposure and separate ligation of the cystic duct and artery always must be attempted. It is true that under most unusual circumstances the cystic artery and the duct must be ligated with a single tie; however, this is the exception and not the rule. The foramen of Winslow and its boundaries are surgical guides which aid in the performance of safe gallbladder and common duct surgery. The foramen is found readily by placing a finger along the free margin (right side) of the lesser omentum; this locates the foramen and permits the finger to enter the lesser peritoneal cavity. The boundaries around a finger so placed in the foramen are: cephalad to the finger, the gallbladder is found; caudad, is the superior margin of the first part of the duodenum; on the palpating finger is the lesser omentum which contains 3 structures, namely, the common duct, the portal vein and the hepatic artery (the duct and the artery lie on the vein); behind the finger is the inferior vena cava. If the cystic artery retracts or if there is bleeding during the course of biliary surgery, it is wise to place the index finger in the foramen of Winslow and grasp the hepatic artery between the index ringer and the thumb. Pressure so made will control the bleeding, since the cystic artery arises from the hepatic. It is wise also to place a gauze sponge in the foramen of Winslow during biliary surgery to prevent injury to the inferior vena cava, and also for immediate orientation.The lymphatics of the gallbladder drain into the lymph glands at the hilus of the liver and into the liver substance.
GALLBLADDER SURGERY
CHOLECYSTOSTOMY This operation is reserved for the poorrisk patient with acute progressive infections of the gallbladder or in those cases where removal of the organ would be technically difficult or too dangerous. The gallbladder is exposed, and a trochar is inserted into its lumen; its liquid contents are aspirated; and any stones which are present are removed. After aspiration, the organ can be grasped with noncrushing forceps. The opening is enlarged; a rubber tube is inserted into the lumen and is held there by a transfixing suture. A purse-string suture or interrupted inverting sutures are placed about the opening in the gallbladder and tightened around the tube. Some surgeons advocate additional drains.
CHOLECYSTECTOMY A right rectus incision which divides the muscle at its inner third usually is used. The fundus of the gallbladder is grasped and lifted upward. A hemostat is placed on Hartmann’s pouch, and lateral and upward traction is maintained so that the cholecystoduodenal ligament is placed on a stretch. It will be remembered that these two structures, Hartmann’s pouch and the cholecystoduodenal ligament, are the surgeon’s two most important guides. The left index finger is placed in the foramen of Winslow, and the boundaries around this foramen are reviewed quickly. The cholecystoduodenal ligament is snipped carefully and spread so that the proper cleavage plane is entered. This permits mobilization of Hartmann’s pouch; the cystic duct then comes into view. The cystic artery usually is found medial and cephalad to the cystic duct. The cystic duct and the cystic artery are ligated individually. Ligation of the cystic duct should be done about 1 to
CHOLEDOCHOSTOMY Any one of the 4 parts of the common duct may require exploration. This usually can be accomplished through its first or supraduodenal portion. A longitudinal incision about
FIG. Cholecystostomy. (A) The distended gallbladder is steadied by the hand of the surgeon as an aspirating trocar is placed into the lumen of the organ. (B) A Pezzer catheter is sutured into the gallbladder for purposes of drainage.
FIG. Choledochostomy. (A) An incision is made into the lesser omentum and the supraduodenal part of the common duct. (B) The stone is removed, and a “T”-tube is inserted into the common duct. (C) The “T”-tube is in place, and the gallbladder is removed from below upward.
common duct between the cystic duct and the duodenum. The cut edges of the duct are grasped, a blunt curved probe is passed downward to the ampulla of Vater and, if possible, into the duodenum. The hepatic duct is explored. After determining the patency of the ampulla of Vater, a “T”- tube is inserted into the common duct; it is fixed there and the duct is sutured around the neck of the tube. This is reinforced further by a few sutures placed in the lesser omentum. For exploration of the third part of the common duct (infraduodenal or pancreatic portion), it becomes necessary to mobilize the descending part of the duodenum. This is accomplished by incising the parietal peritoneum along the lateral border of the descending duodenum, permitting medial rotation of the latter. Although some authors state that this renders the intrapancreatic portion of the common duct accessible, this is usually not true, because the duct lies within pancreatic tissue and is surrounded by blood vessels. If a stone is impacted in part 4 (intraduodenal portion) of the common duct, it can be approached transduodenally.
FIG. Approach to the pancreatic portion of the common bile duct.
CHOLECYSTO-ENTEROSTOMY In certain types of obstructive jaundice it may be necessary to perform an anastomosis between the gallbladder and some part of he small bowel, namely, duodenum or jejunum; cholecystogastrostomies also have been done. These procedures are discussed under surgery of the pancreas.
Spleen
EMBRYOLOGY To understand the peritoneal attachments of the spleen and their surgical applications, the embryologic changes which take place must be understood. The stomach (before rotation) is attached posteriorly by a dorsal mesogastrium and anteriorly by a ventral mesogastrium. The spleen originates as a localized cellular collection in the left layer of the dorsal mesogastrium. These cellular collections fuse with one another to form a lobulated spleen, the notch or notches of which are the only surface traces of lobulation in the adult organ.
The spleen divides the dorsal mesogastrium into: (1) a gastrosplenic part and (2) a spleno-aortic part (lienorenal ligament). As growth takes place, the spleen and the stomach shift to the left, and the liver shifts to the right. The spleno-aortic ligament is pushed against the posterior abdominal wall, and a fusion takes place between the two opposed surfaces. The splenoaortic ligament, having been pulled to the left, comes in contact with the left kidney; because of its new position, it is referred to as the linenorenal (splenorenal) ligament. The splenic artery runs in the lienorenal ligament. To mobilize the spleen it becomes necessary to incise the left leaf of the lienorenal ligament and to enter the fusion (cleavage) plane behind the splenic artery. This converts the lienorenal ligament back to its early form, namely, the spleno-aortic ligament. It is a bloodless maneuver and will be discussed under the heading of “Splenectomy.” That part of the dorsal mesogastrium which is located between the greater curvature of the stomach and the spleen is the gastrosplenic omentum; it contains continuations of the splenic artery known as the vasa brevia. The lienorenal ligament and the gastrosplenic omentum form the splenic pedicle, which connects the spleen to the kidney and the stomach; this pedicle consists of 4 layers.
ADULT SPLEEN The spleen is covered completely by peritoneum except at the hilum. It presents 4 surfaces: (1) a posterior surface which is convex and lies in contact with the diaphragm, (2) an anterior surface toward the stomach, (3) an inferior surface, which is small and rests on the splenic flexure of the colon and (4) an internal, which is in contact with the left kidney. The hilum is on the anterior or gastric surface, and posterior to it is a depression which lodges the tail of the pancreas. Vessels and nerves enter and leave at the hilum, and the lienorenal and the gastrosplenic ligaments attach here.A phrenicocolic (costocolic) ligament runs from the splenic flexure of the colon to the diaphragm opposite the 10th and the 11th ribs. This ligament is usually avascular and forms a floor on which the spleen rests, thus giving it additional support; it is of surgical importance in the mobilization of the spleen and the splenic flexure. The adult spleen is placed high in the left
posterior corner of the abdomen and lies deep to the 9th, the 10th and the 11th left ribs; its long axis corresponds to that of the 10th rib. The peritoneal cavity, the diaphragm and the pleural cavity separate it from the ribs; the left lung intervenes in its upper third. If the surgeon stands to the right of the patient and passes his right hand above the phrenicocolic ligament, he will be able to follow the diaphragm posteriorly, and the spleen will fall into his hand. At times, adhesion of variable density attach the spleen to the diaphragm; these must be severed before the organ can be mobilized properly. The exploring hand is stopped by the left layer of the lienorenal ligament
VESSELS The splenic artery passes to the left, along the upper border of the body and the tail of the pancreas and across the left kidney to reach the spleen The artery does not enter the spleen as a single large vessel but breaks up into from 5 to 8 terminal splenic branches. The splenic vein is formed at the hilum of the spleen and is joined by the left gastroepiploic and other veins from the greater curvature of the stomach. It passes to the right in the lienorenal ligament behind the pancreas and lies below the splenic artery. Behind the neck of the pancreas it joins the superior mesenteric vein to form the portal vein; in its course it receives the inferior mesenteric vein. Accessory splenic tissue has been found in 11 per cent of autopsy material (Adami); the most common sites are near the hilum, the mesentery or the omentum, the tail of the pancreas and the bowel wall (Gray).
SPLENECTOMY This operation has been performed for injuries to the spleen, hemolytic jaundice, Gaucher’s disease, splenic anemia, tumors, cysts, hypersplenism and splenomegaly which produces pressure symptoms. Many incisions have been described, including a thoracico-abdominal approach. The one preferred by Warren Cole is a curved oblique incision which starts high in the epigastrium about % inch to the left of the midline and extends downward for a distance of
FIG. The spleen in relation to the 10th rib. The cut splenic pedicle and its contents also are shown.
FIG. Splenectomy. (A) Long left rectus incision. (B) The gastrosplenic ligament has been divided, and the vasa brevia have been ligated. An incision is made in the posterior parietal peritoneum, and the splenic artery is ligated. (C) The left leaf of the lienorenal ligament is cut. (D) The spleen is delivered, and individual ligation of the splenic vessels is accomplished. (E) Mobilization and removal of the spleen by dividing (1) the gastrosplenic ligament, (2) the left leaf of lienorenal ligament and (3) the right leaf of lienorenal ligament.
severed. The vessels which run in the gastrosplenic ligament (vasa brevia) are ligated. Cole is of the opinion that preliminary ligation of the splenic artery makes for better surgery. The posterior parietal peritoneum is incised over the upper border of the pancreas where the splenic artery is found. Since the artery runs a tortuous course, it humps over the upper border of the pancreas and can be seen, felt and ligated here. The incision into the left leaf of the lienorenal ligament is next accomplished to permit further mobilization of the spleen. This is divided, and the cleavage plane which permits delivery of the spleen and the splenic vessels is entered. If it is impossible to see this leaf of peritoneum, it can be divided blindly over the upper pole of the kidney. This step has been considered by many as a key to the operation, since this left leaf of lienorenal ligament anchors the spleen. When this ligament is cut, the spleen becomes mobile and can be drawn out through the abdominal incision. Following delivery, the vessels are ligated individually as they pass under cover of the right leaf of the lienorenal ligament. The tail of the pancreas and the stomach should be carefully retracted and visualized before the clamps are applied to the remainder of the splenic pedicle so that these structures are not injured.
Blood Supply of the Gut
The primitive gut is divisible into 3 parts: foregut, midgut and hindgut. The foregut ends and the midgut begins where the bile duct enters the duodenum; the midgut ends, and the hindgut begins at the junction of the right and the middle thirds of the transverse colon. Each of the above 3 portions has its own blood vessel, as follows: (1) the foregut is supplied by the celiac artery, (2) the midgut is supplied by the superior mesenteric artery, (3) the hindgut is supplied by the inferior mesenteric artery. The celiac artery supplies the stomach and the duodenum to the entrance of the bile duct and its associated glands, the liver, the pancreas and the spleen; the superior mesenteric artery supplies the duodenum distal to the entrance of the bile duct, the jejunum, the ileum and the colon almost as far as the left colic flexure; the inferior mesenteric artery supplies the descending colon, the sigmoid and the rectum. Only the more common vascular patterns will be described; the student must always remember that anatomic variationsmust continually be kept in mind.
CELIAC ARTERY (CELIAC AXIS) The celiac artery (celiac axis) is the first branch of the abdominal aorta; it is short, about 1/2 inch long, and thick. The artery originally arose at the level of the 7th cervical vertebra, but during development, the lungs pushed the diaphragm caudally, and the diaphragm in turn forced the stomach and the celiac vessel downward. Therefore, in its final position the median arcuate ligament, which unites the two crura of the diaphragm, lies immediately above the artery, and the crura are on each side of it. The vessel cannot be seen until the lesser omentum is incised, and then it is found immediately above the pancreas and behind the posterior parietal peritoneum. It is found at the level between the last thoracic and the 1st lumbar vertebrae. After passing almost horizontally forward for 1/2 inch it trifurcates into (1) the left gastric artery, (2) the splenic artery and (3) the hepatic artery. Left Gastric Artery (Coronary Artery). This is the smallest of the 3 branches. It runs
FIG. A diagrammatic representation of the embryology of the foregut, the midgut and the hindgut, and the blood supply to each of these and their derivatives.
obliquely upward and to the left until it nearly reaches the esophagus; it then arches sharply forward to reach the lesser curvature of the stomach. In so doing it drags a fold of peritoneum with it; this forms a “mesentery” for the vessel, known as the left gastropancreatic fold. In its course it first lies on the left crus of the diaphragm behind the lesser sac; it then passes into the gastropancreatic fold and finally continues between the layers of the lesser omentum. When it reaches the stomach, it supplies esophageal branches which pass upward and anastomose with esophageal branches of the thoracic aorta. Its branches are distributed to both surfaces of the stomach; these anastomose with the short gastric branches of the splenic and the gastroepiploic arteries. Splenic Artery (Lineal Artery). This is the largest branch of the celiac artery and is remarkable for its tortuosity. It travels to the left along the upper border of the pancreas, into which it sends branches. It crosses the left crus of the diaphragm, the left adrenal gland and the upper part of the left kidney. It then enters the lienorenal ligament, through which it gains entrance to the hilum of the spleen by means of 5 to 8 terminal splenic branches. Short gastric arteries (vasa brevia), from 4 to
passes along the lesser curvature of the stomach and anastomoses with the left gastric artery. The hepatic artery continues upward to the porta hepatis, where it divides into right and left hepatic arteries which are distributed to corresponding lobes of the liver. The cystic artery is usually a branch of the right hepatic artery, MESENTERIC VESSELS Superior Mesenteric Artery. This vessel constitutes a vascular axis around which early rotation takes place. After rotation, those branches which originally arose from the right side of the vessel now arise from the left, and vice versa. This vessel originates from the front of the aorta about 1/2 inch below the origin of the celiac artery and opposite the first lumbar vertebra. At its origin it lies behind the pancreas and the splenic vein. Where it passes in front of the duodenum it is crossed anteriorly by the transverse colon; in the lower part of its course it lies behind the coils of the small intestine. Although the superior mesenteric artery and vein lie behind the body of the pancreas, they pass anterior to the uncinate process of the head of the pancreas. The vessel takes a downward and forward course, descending between the layers of the mesentery to the right iliac fossa where, considerably diminished in size, it anastomoses with one of its own branches, the ileocolic artery. As it travels in the root of the mesentery it crosses the third part of the duodenum, the aorta, the inferior vena cava, the right ureter and the psoas major muscle in the order named. Its branches are: the inferior pancreaticoduodenal, the intestinal (jejunal and ileal), the ileocolic, the right colic and the middle colic arteries; although mentioned last, the middle colic artery is really the first branch. Inferior Pancreaticoduodenal Artery. This artery arises opposite the upper border of the transverse (third) portion of the duodenum. It courses to the right between the head of the pancreas and the duodenum, passing behind the superior mesenteric vein. The vessel divides into anterior and posterior branches which anastomose with corresponding anterior and posterior branches of the superior pancreaticoduodenal artery and in this way forms 2 vascular arches: one in front of the right margin of the head of the pancreas and the other behind it. These arches supply the head of the pancreas and, by means of the straight vasa recta, supply the corresponding part of the duodenum. Of surgical importance is the fact that the pancreatic part of the common duct descends between these arches. Jejunal and Heal Arteries. From 10 to
The portal vein is formed behind the neck of the pancreas by the union of the superior and the inferior mesenteric veins and the splenic veins. It passes upward and to the right behind the first part of the duodenum, and at the upper border of the duodenum it enters and ascends in the lesser omentum; it then divides into right and left branches. In its course it receives the left and the right gastric veins from the lesser curvature of the stomach, as well as the pancreaticoduodenal vein. Although this pattern of the formation of the portal vein is described frequently, it must be emphasized that many other patterns are possible. Rousselot has emphasized the importance of such variations in the clinical behavior of patients suffering with congestive splenomegaly (Banti’s syndrome). The portal vein delivers to the liver blood which has circulated through the spleen, the pancreas and through the whole length of the alimentary tract from the lower end of the esophagus to the upper end of the anal canal. The hepatic veins carry blood from the liver to the inferior vena cava, which lies in a groove on the posterior aspect of that organ. When the liver becomes diseased, the portal vein may become obstructed, as in cirrhosis of the liver. Communications exist between the portal vein and the inferior vena cava (portacaval communications). These anastomoses exist but do not function unless obstruction to the portal vein, either in its intraperitoneal or intrahepatic course, is present. Such communications have been referred to as the accessory portal system, and are found at the following places. 1. At the lower end of the esophagus the esophageal branches of the left gastric veins (portal) anastomose with the esophageal branches of the azygos veins (caval). In portal obstruction these esophageal veins may become varicosed and dilated and produce large varices which project into the esophageal mucosa. Since they are unsupported, they may rupture when the patient is in apparently good health; this results in an exsanguinating hemorrhage; they have been referred to as “esophageal piles.”
FIG. The portal system of veins. The usual pattern of this system is presented; however, many variations are possible.
FIG. Variations in the pattern of the portal system.
4. Around the umbilicus, veins passing along the falciform ligament to the umbilicus connect the veins of the liver (portal) with the epigastric veins around the umbilicus (caval). Enlargement of these veins produces the so-called caput Medusae. Although connections exist between these two venous systems, they seldom suffice to produce a portal compensation when the portal system is obstructed. In an attempt to communicate the portal and the caval systems, surgical procedures which result in portacaval and splenorenal shunts are now being done. At present the results of these operations are quite encouraging.
FIG. Embryology. (A) Early stage of development before fusion has taken place. (B) After fusion of the ascending mesocolon with mesoduodenum; posterior fixation of the colon is also shown.
SMALL INTESTINE
The small intestine (duodenum, jejunum and ileum) has an average length of
FIG. Embryology of the duodenum. (A) Cross section through the duodenum and the mesoduodenum before rotation of the gastroduodenal segment. The arrow presents the direction of rotation against the right primitive parietal peritoneum. (B) The same as “A,” after fusion has taken place. The surgical cleavage plane for mobilization of the duodenum and the head of the pancreas is indicated.
vessels approaching the bowel are present in the more proximal part of small bowel but are absent in the distal portion. The jejunoileum fills the space below the transverse colon and the mesocolon and more or less overlies the ascending and the descending colons; it rests on the iliac fossae and is related to the pelvic viscera. The great omentum hangs down from the transverse colon and, depending on its degree of development, separates the intestines from the anterior abdominal wall. No small intestines occupy the fetal pelvis, but in the adult pelvis the amount depends on the state of distention of the bladder and the rectum and upon the position of the pelvic colon.
DUODENUM Embryology. The rotation of the intestines to their ultimate abdominal positions is produced by drawing the initial colic segment to the right so that the duodenojejunal junction and the small intestines lie toward the left. This
FIG. The duodenum. (A) The relations of Parts 1 and 2 of the duodenum. (B) The 4 parts of the duodenum are shown, and the peritoneal relations of each are resented.
places the duodenojejunal angle against the mesentery of the terminal intestine, with which it fuses. The degree of fusion accounts for the fossae and the peritoneal folds which are found in this region. These fossae and folds are of surgical interest, since deficient fixation of the angle increases the depth and the capacity of the fossae, and loops of intestines may herniate into them and become strangulated. Hyperfixation of the duodenojejunal angle may fix the duodenum so firmly that it becomes kinked and does not empty properly. The descending duodenum and part of the transverse duodenum fuse with the primitive right parietal peritoneum. The remainder of the transverse duodenum and the ascending duodenum fuse with the descending mesocolon, and the duodenojejunal angle fuses with the transverse mesocolon. The superior part of the ascending mesocolon forms a fusion fascia with the anterior part of the mesoduodenum . Proper cleavage planes can be found easily, and surgical mobilization can be accomplished readily if these embryologic details are kept in mind. Adult Duodenum. The duodenum receives its name because at first it was thought to be
FIG. The ligament of Treitz. (A) The short type of ligament which pulls the duodenojejunal flexure above the transverse mesocolon and results in a “U”-shaped duodenum. (B) The long type of ligament which allows the duodenojejunal flexure to lie below the transverse mesocolon and results in a “C”- shaped duodenum.
the proximal coils of jejunum. This part of the duodenum sometimes overlaps the pelvis of the left kidney. Internally, it lies along the aorta and is adherent to the pancreas; externally, it is found on the inner side of the left kidney. A vascular arch is found in the space which separates the duodenum from the kidney; it has been called the vascular arch of Treitz, This arch is formed by the left colic artery and the inferior mesenteric vein as they ascend together near the left border of the duodenum to the root of the transverse mesocolon. The duodenojejunal flexure, although usually retroperitoneal, may penetrate into the root of the transverse mesocolon. It usually lies to the left of the disk between the 1st and the 2nd lumbar vertebrae but may approach the midline or begin at the middle of the 2nd or even the 3rd lumbar vertebra. Its relation to the transverse mesocolon depends on the length of the ligament of Treitz. Posteriorly, it is in relation to the lumbar portion of the diaphragm; above, it is related to the inferior border of the pancreas, and it is embraced by the concavity of the arch formed by the inferior mesenteric vein before it terminates below and behind the pancreas. The flexure is related to the internal border of the left kidney on its left and, anteriorly, to the posterior wall of the stomach, from which it is separated by the transverse mesocolon. It is overlapped somewhat by the pancreas. The duodenojejunal flexure is fixed by the so-called muscle or ligament of Treitz. The suspensory ligament (muscle) of Treitz is a band of fibrous muscular tissue which extends from the duodenojejunal angle and the ascending portion of the duodenum to the right pillar of the diaphragm. It is triangular in shape and originates from a broad base upon the superior border of the duodenojejunal angle. It passes upward behind the pancreas and in front of the aorta. It is better developed in the more muscular individuals and fixes the duodenojejunal angle to the posterior abdominal wall. The length of the ligament of Treitz determines whether the duodenum will be “U”-shaped or “C”-shaped. If the ligament is long, the duodenojejunal flexure lies below the transverse mesocolon, and the “C”-shaped duodenum results. If the ligament is short, the duodenojejunal flexure lies above the transverse mesocolon, and the “U”-shaped duodenum is found. The surgeon should be able to locate this ligament rapidly and in this way orient himself and “run” the intestinal tract (jejunoileum) in search of pathology; he is also able to select that segment of small bowel which he wishes to utilize in a gastrointestinal anastomosis. The ligament and the angle are found in the following way: the surgeon’s left hand grasps the greater omentum and the transverse colon, and, maintaining upward traction on these structures, the transverse mesocoion is made taut. Then the right hand is placed on the lower surface of the stretched transverse mesocolon and follows it posteriorly to its attachment in the region of the first lumbar vertebra; the hand is placed to the left and immediately encounters the duodenojejunal angle with the ligament of Treitz immediately above it.
Arteries. Since the relationship of the duodenum to the head of the pancreas is so intimate, their blood supplies naturally overlap. Many vascular patterns and anomalies have been described; nevertheless the most constant vascular patterns and those of greatest surgical significance are described herein. Pierson has made an accurate study of this region, and much of his material is of practical value. The gastroduodenal artery is a branch of the hepatic artery and arises dorsal and superior to the pyloroduodenal junction. It courses downward, medial to the common duct, and terminates at the lower border of the first part of the duodenum by dividing into the right gastroepiploic and the
anterior superior pancreaticoduodenal arteries. The gastroduodenal artery gives off a posterior superior pancreaticoduodenal artery as it passes dorsally to the superior margin of the duodenum. The first part of the duodenum receives 2 smaller branches, namely, the supraduodenal artery to the superior wall and the anterior surface, and the retroduodenal artery which arises about Vi inch above the bifurcation of the gastroduodenal and supplies the lower two thirds of the posterior wall; it sometimes extends as far as the second part. The remainder of the first part of the duodenum is supplied by branches from the right gastroepiploic and the superior pancreaticoduodenal arteries. The superior anterior and posterior pancreaticoduodenal arteries anastomose with corresponding anterior and posterior inferior pancreaticoduodenal arteries from the superior mesenteric. In this way two arterial arcades are formed, one on the posterior surface of the head of the pancreas and the other on the anterior surface. They are called respectively, the posterior and theanterior arcades of the pancreas. The 2 inferior pancreaticoduodenal arteriesarise from a common trunk from the superior mesenteric called the common inferior pancreaticoduodenal artery. From the 2 arterial arcades the duodenum receives anterior and posterior sets of vasa recta. Shapiro and Robillard have stressed the possible dangers (“blowouts” and leakage) which might result from injury and ligation of
FIG. The 5 duodenal fossae. (A) The paraduodenal fossa. Enlargement of this fossa must be made in a downward direction to avoid the inferior mesenteric vein. (B) The superior and the inferior duodenojejunal fossae formed by 2 peritoneal folds. (C) The inferior duodenal fossa extends behind the third part of the duodenum. (D) The mesentericoparietal fossa is located behind the first part of mesojejunum.
the vasa recta during a too radical mobilization of the duodenal stump from the pancreas in the course of a gastric resection. They further stress the futility of thorough ligation for the control of hemorrhage from a duodenal ulcer, stating that such a procedure is tantamount to complete devascularization of the duodenum and the head of the pancreas. The nerves are derived from the celiac and the superior mesenteric plexuses and follow the course of the arteries. The lymphatics of the duodenum are closely related to those of the pancreas. There are anterior and posterior sets of glands which drain into the superior pancreatic and pancreaticoduodenal lymph glands on the anterior and the posterior aspects of the groove between the duodenum and the pancreas. The efferent vessels from these glands pass in two directions: upward to the hepatic lymph glands and downward to the preaortic lymph glands around the superior mesenteric artery. There are also some communications with the lymphatics of the ascending colon and the appendix. Duodenal Fossae. There are 5 duodenal fossae which may be encountered. 1. The paraduodenal fossa lies to the left of the duodenojejunal flexure and opens to the right and upward. It occurs in about 20
FIG. The jejuno-ileum. (A) The normally placed coils of jejunoileum: the jejunum is above and to the left, and the ileum is below and to the right. (B) The stretched root of mesentery. (C) The jejunoileum has been removed, and the convolutions of the mesentery are shown.
per cent of people and rarely, if ever, exists with any other type of duodenal fossa. It is bounded on the right by the aorta, on the left by the kidney, above by the pancreas and the renal vessels and anteriorly by the inferior mesenteric vein which runs in the anterior wall of the fossa. This anterior relationship is of surgical importance, since a hernia into this fossa may press upon the inferior mesenteric vein and produce hemorrhoids. In case this fossa is the site of a strangulated hernia, its surgical enlargement should be brought about in a downward direction; in this way injury to the inferior mesenteric vein is avoided. 2. The superior duodenojejunal fossa faces downward, is about
THE JEJUNO-ILEUM The jejunum and the ileum together measure about
FIG. Localization of the jejuno-ileum. (A) About
FIG. The root of the mesentery. In its oblique course downward the root of the mesentery crosses the third part of the duodenum, the abdominal aorta and the right psoas muscle.
connects the intestines to the posterior abdominal wall and conveys vessels and nerves to and from it is called a mesentery. The mesentery proper connects the coils of jejunoileum to the posterior abdominal wall below the line of attachment of the transverse mesocolon. Its root or radix (parietal attachment) extends from the left side of the 2nd lumbar vertebra downward and to the right to the right sacro-iliac joint, a distance of about
MECKEL’S DIVERTICULUM This outpouching resembles the finger of a rubber glove extending at right angles from the terminal ileum opposite its mesenteric attachment. Such a diverticulum usually occurs within the terminal two feet of ileum, is usually two inches long, is present in two per cent of all people and occurs two to one in favor of males. In the human embryo, the convexity of the umbilical loop of the primitive gut communicates with the yolk sac by the omphalo (vitello) intestinal duct. This duct normally becomes occluded and should disappear entirely; however, all or part of it may persist. If the duct remains completely patent, a congenital fecal fistula results at the umbilicus. The commonest anomaly of this duct is a blind diverticulum which is attached to the ileum; this has been described as a Meckel’s diverticulum. As a rule, it has the same diameter as the gut from which it arises; its end may be free or attached to the umbilicus by a fibrous cord. The vessel which accompanies such a diverticulum is the terminal part of the superior mesenteric artery; therefore, a Meckel’s diverticulum has an artery of its own. It is important to remember that such diverticula may have ectopic pancreatic or gastric tissue contained within. These islands of digestive tissue appear at two sites, namely, at the blind end of the diverticulum or at its base where it attaches to the ileum. Therefore, it is important that a wide excision of the base or even a resection of the attached ileum be done. When a simple diverticulectomy is performed, the enzymes may be activated by the surgery, and the sutures (catgut) are digested; this may result in a fatal peritonitis.
SURGICAL CONSIDERATIONS
OPEN AND CLOSED ANASTOMOSES Open Method of Small Bowel Anastomosis. Removal of part of the small intestine (enterectomy) is done for tumors, trauma and gangrene of the bowel. Clamps are applied in such a way that the tissue to be removed is placed in crushing clamps, and the tissue which remains for the anastomosis is held by nontraumatizing clamps. Following removal of the mass, the intestinal clamps are placed side by side, and a posterior seroserous suture line, either interrupted or continuous, is placed. A Maunsell mesenteric stitch is placed, and a traction suture is utilized on the antimesenteric borders of the bowel. The Maunsell stitch is important, since it protects the mesenteric triangle which is deficient of peritoneum and also ligates the vessels along the mesenteric border. Then a posterior layer of through-and-through sutures is placed. This is followed by an anterior through-and-through suture, the clamps are removed, and the anterior seroserous suture completes the anastomosis. The rent in the mesentery is closed. Closed “Aseptic” Method of Anastomosis. Four crushing clamps are placed on the
FIG. Superior mesenteric artery. This vessel passes in front of the third part of the duodenum and supplies the distal part of the duodenum, the jejuno-ileum and the right half of the colon.
bowel, and the diseased mass is resected. A continuous or interrupted suture method may be used; the former will be described. The suture starts on the side opposite the surgeon and passes at right angles to the clamp; following this, the suture passes parallel with the clamps and ends on the opposite side to which it started. The handles are reversed, and the same type of suture is placed again. The forceps are removed, and the sutures are tied. The lumen is opened by finger pressure to either side of the invaginated tissue. The operation is completed by a layer of interrupted or continuous seroserous sutures, and the margins of the mesentery are sutured.
FIG. Meckel’s diverticulum: (A) view of the interior of the diverticulum with possible locations of ectopic gastric or pancreatic tissue, (B) external view.
FIG. Open method of small bowel anastomosis: (A) clamps placed and bowel resected, (B) posterior seroserous layer, (C) posterior through-and-through layer,(D) anterior through-and-through layer, (E) anterior seroserous layer.
ENTEROSTOMY In this operation an artificial fistulous opening is created between the lumen of the small bowel and the body surface. It may be temporary or permanent. If jejunum is used, the operation is known as a jejunostomy; if the ileum is used, it is called an ileostomy. Many methods and modifications have been described, but they all utilize the principles of opening the bowel, transfixing the tube and peritonizing with some method of invagination or tunneling.
LARGE INTESTINE (
Following the stage of the formation of a distinct intestinal loop, a torsion takes place about the superior mesenteric artery. Following this primary torsion, the small intestine begins to lengthen so rapidly that the abdominal cavity cannot retain it; hence, a temporary but “normal” umbilical hernia results. By contrast, the large intestine and its associated mesenter grow relatively little at this period. In embryos of 10 weeks the abdominal cavity has increased sufficiently in size to permit the intestines to return. Probably because of the cecal swelling, the large intestine is the last to leave the umbilical cord and re-enter the abdominal cavity. The cecum, the ascending colon and approximately half of the transverse colon are derived from the midgut, the remainder of the large bowel being derived from the hindgut. The cecum becomes fixed on the right side close to the crest of the ileum. At this stage, however, the colon passes obliquely upward to the left of the stomach, where it curves sharply to form the splenic flexure and continues as the future descending colon. As the liver decreases in relative size, a hepatic flexure appears in the originally oblique proximal colon; this flexure demarcates ascending from transverse colon. Posterior peritoneal fixations of the colontake place so that the ascending mesocolon and the colon fuse with the right parietal peritoneum and the anterior surface of the descending duodenum and its mesentery; the descending colon fuses with the left parietal peritoneum. The mesentery to the remainder of small bowel remains free and unfused. These various fusions may be complete or incomplete; they form surgical cleavage
FIG. Embryology of the large bowel. Sections la and 2a are cross sections before posterior fixations have taken place. Sections lb and 2b are corresponding cross sections after posterior fixations have taken place.
planes which permit proper bloodless mobilization of a given segment of bowel. The transverse colon and the mesocolon do not fuse with the posterior parietal peritoneum but hang suspended from the posterior abdominal wall and remain fixed at the two colic angles. The redundant sigmoid loop does not fuse with the left pelvic peritoneum. The upper boundary of the mesosigmoid is the retrosigmoid or intersigmoid recess (fossa), the depth of which depends on the inferior limit of fusion of the descending
FIG. Embryology of the large bowel: (A) before posterior fixation; (B) after posterior fixation.
mesocolon. Into this recess a loop of small bowel may herniate and strangulate. The rectum is the only part of the entire alimentary tube which maintains its primitive sagittal position; it has no mesentery.
LARGE INTESTINE PROPER The differences between the small and the large intestines may be listed as follows:
1. The large bowel is sacculated; the small bowel is smooth.
2. The large bowel has taeniae coli; the small bowel has none. One of the taeniae lies along the line of the mesenteric attachment, and the other 2 are equidistant from it and from each other. All 3 converge on the cecum to the base of the vermiform appendix. These taeniae are explained by the fact that the outer longitudinal muscle of the large bowel does not form a complete coat as it does in the small intestine. It is arranged in 3 narrow longitudinal bands which are shorter than the gut itself, thereby causing a puckering and forming sacculations. If the taeniae are cut, the sacculated form is lost.
3. The large bowel has appendices epiploicae; the small bowel has none. These are little fatty tags which project from the serous coat of the large intestine. Those in the region of the appendix, the cecum and the rectum generally contain little fat; they may even be absent in these areas. Most of them are attached to the colon between its internal margin and the anterior taenia. In the iliac and the pelvic regions the appendices appear in two rows, one on each side of the anterior taenia. 4. The largest intestine has a greater calibre than the small bowel. The size of the colon diminishes from its cecal extremity, the diameter of which is usually
5. Internally, the large intestine has no aggregated lymph nodules, villi or circular folds, all of which are present in the small intestine. The mucous membrane of the large bowel is thrown into folds opposite the constrictions between its sacculations. These folds are not permanent as in the small bowel; hence, the former can be smoothed when the longitudinal muscle bands are cut. The large bowel begins in the right iliac fossa as a blind head, called the cecum, to which the vermiform appendix is attached. The cecum continues upward into the ascending colon, which lies on the right half of the posterior wall of the abdomen. At the inferior surface of the liver, the ascending colon makes a sharp bend medially to form the right colic (hepatic) flexure, which lies on the anterior surface of the right kidney; it continues as the transverse colon. The latter crosses the abdomen transversely to the lower part of the spleen and on the front of the left kidney; it makes a sharp bend to form the left colic (splenic) flexure, which passes into the descending colon. This continues down the left side of the posterior abdominal wall to the iliac crest, then downward and medially in the left iliac fossa to end at the medial margin of the psoas major muscle as the pelvic (sigmoid) colon. This part of the colon hangs into the pelvis as a loop and ends at the middle of the middle piece of sacrum; it continues as the rectum. The primitive mesentery possessed by the large bowel in fetal life is retained by only two parts of the large intestine, namely, the transverse and the pelvic colons. The extent to which the ascending and the descending colons are surrounded by peritoneum is variable. They usually are surrounded on 3 sides and remain bare posteriorly. However, it may be completely surrounded by peritoneum but have no mesentery; finally, the mesentery may persist wholly or in part. Because of its usual method of fixation, the position of the large bowel is more constant than that of the small bowel. The large bowel is 5 or
CECUM The ileocecal region and the attached appendix form an important surgical and structural unit. During early development the cecal segment forms a tube of uniform dimension. However, the lower part of the cecal segment lags in growth, while the upper part continues to increase with the rest of the colon. This difference in size becomes greater, and finally the lower tapering extremity becomes the vermiform appendix, and the larger part situated directly above it becomes the cecum. At birth, the cecum has a conical smooth external appearance, but by the 3rd year longitudinal bands or taeniae with sacculi between them are present. The sacculus between the anterior and the lateral bands develops more rapidly and out of proportion to the others. This large sacculus forms the most dependent part (fundus) and constitutes the greater part of the anterior wall of the cecum. The appendix is attached medially and posteriorly; it is not associated with this large cecal sacculus. The cecum, or head of the colon, as it has sometimes been referred to, is a blind pouch which normally is found in the right iliac fossa. It is that portion of large intestine which is below the ileocecal valve and is usually 2 1/2inches long and 2 1/2 inches wide. It has a more-or-less complete peritoneal investment, which accounts for its having a certain degree of mobility, but it is held in place because of its continuity with the ascending colon. From its anterior surface the peritoneum is continuous upward over the ascending colon, but from the upper part of its posterior surface the peritoneum is reflected backward and downward over the iliac muscle, thereby forming a small cul-de-sac behind the cecum; this is known as the retrocecal recess. When such a recess or fossa is well developed, it frequently contains the vermiform appendix. Posteriorly, the cecum rests on the iliopsoas muscle, the lateral cutaneous nerve of the thigh (femoral nerve) and very often the external iliac artery. When distended it is in contact with the greater omentum and the anterior abdominal wall, but when collapsed it is covered by a few coils of small intestine. The ileocecal orifice and valve are located internally in its upper half, and the opening of the vermiform appendix is in the posteromedial aspect. The ileocecal valve is a shelflike projection of mucous membrane where the wall of the ileum has become invaginated into the lumen of the cecum. The cecum is not only the widest part of the large bowel, but it is also the thinnest. Because of this, almost all spontaneous perforations of the large intestine occur in this region. The taeniae coli of the cecum are anterior, posterior and medial. They converge on the base of the vermiform appendix, for which they provide a complete longitudinal muscle coat. The position of the cecum may vary. In its low position it may lie in the depth of the pelvis and in its high position, due to incomplete development of the colon, it may occupy a position below the liver and on the right kidney. In the fetus and the infant it lies high; this should be kept in mind when an incision is being contemplated for an appendectomy in children. It usually elongates and descends with advancing age and may be present in the sac of an inguinal hernia. Occasionally, the cecum and the colon retain their posterior fetal peritoneal connections and then are suspended from the posterior abdominal wall by a mesentery which permits a large range of mobility. This makes it possible for the ileocecal segment to become twisted (volvulus) and may also be an etiologic factor in the occurrence of intussusception. Appendices eplipoicae frequently are absent over this portion of the large intestine. Membranes. Accessory peritoneal bands or membranes which are of surgical importance are found in this region. Two in particular warrant mentioning: Lane’s and Jackson’s membranes.
FIG. 343. Accessory peritoneal bands.
Lane’s Heal membrane is a thickening of parietal peritoneum in the region of the right iliac fossa. It extends from this fossa to the antimesenteric border of the last 2 or
FIG. The cecal fossae.
to the anterior longitudinal band of the ascending colon or cecum. A characteristic feature of this membrane is the presence of fine parallel vessels which are seen through it; they rarely, if ever, require ligation. Fossae. The cecal (pericecal) fossae are pouches which are formed in the ileocecal region by peritoneal folds. They are of importance to the surgeon because the appendix may occupy any one of them; herniations into these fossae also have been recorded. The 3 main cecal fossae are the following: (1) The ileocolic (superior ileocecal), (2) the ileocecal and (3) the subcecal (retrocecal). The ileocolic or superior ileocecal fossa lies above the ileocolic junction and is formed by a peritoneal fold which passes across the ileocolic angle. It is bounded anteriorly by the ileocolic fold, which contains the ileocolic artery and vein, and posteriorly by the ascending colon; it opens toward the left. The ileocecal fossa is formed by the socalled ileocecal or bloodless fold of
VERMIFORM APPENDIX Position. In fetal life the appendix opens into the apex of the cecum, but in the adult the opening is an inch below the ileocolic junction. It may occupy any position, depending on its length and its mesentery. Wakeley, in 10,000 cases, found it either to be postcecal or retrocolic in 65.28 per cent of the cases. It has been the impressionof the author that the vermiform appendix is found in a retrocecal position in at least 70 per cent of those cases seen at the operating table and in the cadaver. Although the relation of the base of the appendix to the cecum is quite constant, it may occupy one of many positions. The so-called paracolic position is one in which the appendix is located on the outer side of the ascending colon. In the splenic position, the appendix is entirely intraperitoneal but passes up in the direction of the spleen, either in front of or behind the terminal ileum. The promontoric position is one in which the appendix is directed transversely inward toward the promontory of the sacrum. At times the appendix is pelvic; it then hangs over the pelvic brim and is in the true pelvis. It has also been described as assuming a midinguinal position when it passes down toward the middle of the inguinal ligament. Length. The appendix is usually from 3 to
FIG. The vermiform appendix and the ileocecal region. (A) The appendix is shown lying over the pelvic brim; this is not its most frequent position (see text). (B) Various positions in which the appendix may be found.
involved. Such an abscess may discharge into the bladder, the cecum, the colon or the rectum. Abscesses in the pelvis may be evacuated vaginally or rectally. APPENDECTOMY Since the appendix is a mobile part, and since it may be found almost anywhere in the abdomen, a variety of incisions have been described for its removal. However, this still remains a personal problem with the surgeon. The appendix is located by first making upward traction on the cecum; the ileal fat pad is located and turned to the left. This usually uncovers the appendix which, in most instances, is found retrocecally. If the appendix is not located after dislocating the cecum and the ileal fat pad, one assumes that it is retroperitoneal, and mobilization of the cecum becomes necessary. This is accomplished by incising along the paracecal gutter and dislocating the cecum and the ascending colon to the patient’s
left. When the appendix is delivered, the meso-appendix is clamped and cut; the base of the appendix is ligated with or without clamping. The hemostats on the mesoappendix are replaced by ligatures; if a pursestring is used, this is placed now. A haemostat is placed above the ligated base, and the appendix is removed between this ligature and the clamp. There are many modifications of this procedure.
ASCENDING
RIGHT COLIC (HEPATIC) FLEXURE This is an angle or bend which forms at the junction of the ascending and the transverse colons. It lies in front of the right kidney and under the liver and the gallbladder. It may form an obtuse or an acute
FIG. Appendectomy: (A) McBurney incision; (B) the external oblique, the internal oblique and the transversus abdominis muscles have been incised in line with their fibers; (C) the appendix is located by displacing the cecum upward and the ileal fat pad to the left (assistant); (D) the meso-appendix is clamped and cut; (E) the appendix is amputated between the clamp and the ligature; (F) no inversion technic.
angle but is not as sharp as the angle of the splenic flexure. Medial to it is the second part of the duodenum, and lateral to it is the edge of the liver or the lateral abdominal wall; above, it touches the liver; posteriorly, it lies on the right kidney. It is clothed with peritoneum except on its posterior surface. A peritoneal band from the lesser omentum sometimes passes downward to the flexure; it is called the hepatocolic ligament.
TRANSVERSE COLON The transverse colon measures from 18 to
FIG. Relations of the ascending, the transverse and the descending colons. The numerals indicate the 5 muscles over which the descending colon passes.
FIG. The intercolic membranes.
part of the colon possesses a mesentery (transverse mesocolon), a wide range of movement is possible. It is related anteriorly to the anterior 2 layers of the greater omentum and the anterior abdominal wall; posteriorly, it lies in contact with the second part of the duodenum and the head of the pancreas. In the rest of its extent it is separated from the posterior abdominal wall by coils of jejuno-ileum. The upper border of the transverse colon is separated from the greater curvature of the stomach by the lesser peritoneal sac and the anterior 2 layers of the greater omentum. The transverse mesocolon connects the transverse colon to the posterior abdominal wall. As it suspends the colon, it forms a horizontal partition which separates the cavity of the omental bursa and the supramesocolic structures from the inframesocolic compartment. In this way it acts as a barrier to infection between these areas. The posterior attachment of the transverse mesocolon extends to the anterior surface of the head, the neck and the body of the pancreas but may continue to the right and cross the anterior surface of the second part of the duodenum. The middle colic artery passes between the 2 layers of the transverse mesocolon; although it is called the “middle” colic artery, it should be noted that it passes well to the right. To the left of this vessel is a wide area (avascular area of Riolan) which contains no blood vessels; when incised, it allows the fingers to be introduced into the lesser peritoneal cavity. The great variations in the position of the transverse colon result in the formation of a “V”-shaped or “U”-shaped bend. Within the female pelvis a pendulous transverse colon may acquire adhesions which attach to the uterus, the ovaries and the fallopian tubes, thus causing a kink sufficient to produce an obstruction. Abnormally long transverse colons have been found not only in ventral and umbilical hernias but also in inguinal and femoral hernias. As the transverse colon passes from right to left it ascends; thus the splenic flexure is placed at a higher level than the hepatic. The transverse colon is covered on its posterior surface with the peritoneum of the general peritoneal cavity, but on its anterior surface it has acquired a covering of peritoneum of the omental bursa. Peritoneal bands may produce “normal” kinking of the transverse colon. Two such bands which are found most commonly associated with this part of the colon are the mesocolicojejunal membrane and the intercolic membrane. The mesocolicojejunal membrane is a band which extends from the undersurface of the transverse mesocolon to the antimesenteric border of the first part of the jejunum. The intercolic membranes are peritoneal folds which bind together the ascending colon and the proximal part of the transverse colon, and the descending colon and the distal part of the transverse colon. If these intercolic membranes are present, they cause the so-called “double-barreled” colon and have been considered a cause of partial large bowel obstruction.
LEFT COLIC (SPLENIC) FLEXURE This lies at a higher level and on a deeper plane than the right; it also forms a sharper bend. It is limited above by the tail of the pancreas and the base of the spleen; it rests on the outer border of the left kidney, the diaphragm and the transversus muscle. The phrenicocolic ligament is a fold of peritoneum which connects the splenic flexure to the diaphragm opposite the 10th or the 11th rib. It is bloodless and may be cut with impunity in mobilizing the splenic flexure or during splenectomy. This peritoneal fold aids in the fixation of the left colic flexure and also forms a floor upon which the spleen rests. The posterior surface of the splenic flexure is bare as a rule, but the entire flexure may be enclosed in peritoneum and then is connected with the end of the pancreas by a short fold of transverse mesocolon. Because of the situation and the fixation of this flexure its exposure and mobilization are more difficult than any other part of the large intestine.
DESCENDING
LYMPHATICS OF THE COLON G. Gordon Taylor has remarked that the surgery of cancer is the surgery of the lymphatic system; therefore, a thorough understanding of the regional lymph drainage aids the surgeon when operative intervention is contemplated. In the case of the colon, the involved bowel should be resected well to either side of the malignant growth, together with the lymphatic channels which drain the affected parts. Since the removal of the main artery to a segment of bowel may devitalize that portion of the intestine, it becomes necessary to resect a considerable length of colon. Therefore, typical lesions result in typical resection patterns: 1. Cancer of the cecum and the ascending colon. The blood vessel which supplies this part of the colon is the ileocolic branch of the superior mesenteric artery; it supplies the last 6 to
NERVE SUPPLY OF THE COLON The nerve supply to the large bowel is derived from the autonomic nervous system, except for the lower end of the anal canal, which is supplied by the inferior hemorrhoidal nerve. Therefore, the colon has both sympathetic and parasympathetic fibers. The sympathetic fibers are derived from the lower thoracic and the upper lumbar segments of the spinal cord. They reach the sympathetic chain via corresponding white rami communicantes. The thoracic fibers then proceed to the celiac plexus by way of the lesser splanchnic and possibly the lowest splanchnic nerves. From here they proceed to the superior mesenteric plexus by way of communicating nerves. The fibers which supply the cecum, the appendix, the ascending and the transverse colons originate in the superior mesenteric ganglia, from which nerves pass along the superior mesenteric artery to reach the bowel. Some of the other nerve fibers which leave the superior mesenteric ganglion join the intermesenteric nerves anterior to the aorta. The lumbar sympathetic nerves leave the sympathetic chain via the lumbar splanchnic nerves and join the intermesenteric nerves. The fibers to the descending colon, the sigmoid colon and the upper rectum originate in the inferior mesenteric plexus and follow the course of the inferior mesenteric artery to the bowel wall. The intermesenteric nerves pass downward, anterior to the bifurcation of the aorta, as the hypogastric plexus. This plexus divides into right and left pelvic plexuses, each lying to one side of the rectum; these fibers supply the bladder, the prostate, the pelvic organs and also form the so-called rectal plexus. The parasympathetic fibers arise from both the vagus and the pelvic nerves; these are distributed to the large bowel with the sympathetic fibers. The nervi erigentes are the sacral autonomic nerves which arise from the 2nd, the 3rd and the 4th sacral nerves. They join the pelvic plexuses on each side and are distributed to the bowel with the sympathetic fibers. Some fibers follow the course of the left common iliac artery to the inferior mesenteric artery and are distributed to the descending colon and the sigmoid. The pudendal nerve originates from the 2nd, the 3rd and the 4th sacral nerves; it accompanies the internal pudendal artery. It enters the perineum, runs in Alcock’s canal and gives off the inferior hemorrhoidal nerve, which reaches the external sphincter and the lower cutaneous part of the anal canal.
LARGE BOWEL SURGERY
CECOSTOMY A cecostomy may be performed either as an emergency procedure for large bowel obstruction or as an elective procedure preliminary to operations on the colon. The so-called “blind” type of cecostomy is a simple and efficient method for decompression. A modified McBurney incision is made close to the anterior superior iliac spine, and the cecum is identified and delivered. Two noncrushing clamps are placed on a longitudinal band, and a piece of gauze is placed between the cecum and the parietal peritoneum. The clamps are taped in place. At least 3 hours are permitted to elapse for walling-off, and then an incision is made between the clamps and into the cecum; a mushroom catheter is sewed into the cecal lumen.
COLOSTOMY The Devine colostomy has been called a “defunctioning” operation because the contents of the proximal colon are prevented from entering the distal colon. Devine has resected successfully segments of the left half of the colon with primary suture of the sigmoid to a short rectal stump. In performing a loop colostomy, the portion of bowel selected is brought out through the incision, and a small opening is made in its mesentery near the bowel wall. Through this opening a tape or a rubber tube is passed for traction. The peritoneum is closed beneath the loop with 2 or 3 sutures; the anterior fascia and the skin also are sutured beneath the loop in the same manner. The closure of the wound is completed with interrupted sutures placed above and below the loop. A glass rod or a rubber tube is placed beneath the loop to prevent retraction.
RESECTION OF THE COLON In malignant diseases involving the right side of the colon, a segment should be removed which includes the terminal 6 or
FIG. Nerve supply of the large bowel.
FIG. Side view of the nerve supply to the lower part of the large bowel and to the anal canal.
FIG. Right hemicolectomy. This resection includes the last 6 to
ligated; 2 clamps are placed on the ileum at the point where it is to be transected, and 2 more clamps are placed on the transverse colon at the point where it is to be removed. The bowel between these clamps is severed. The anastomosis is accomplished by closure of the blind ends of the ileum and the colon, followed by a lateral anastomosis; closure of only the end of the colon with an end-toside ileotransverse colostomy is preferred by some. Most neoplasms which are situated between the middle colic and the superior hemorrhoidal arteries and involve the transverse colon, the splenic flexure, the descending colon, the sigmoid and at times the rectosigmoid may be removed by the Mikulicz exteriorization procedure or by resection with primary anastomosis. Both open and closed anastomoses have their advocates.
FIG. The Mikulicz (exteriorization) procedure. (A) The involved bowel (sigmoid in this case) is mobilized and exteriorized. A spur has been formed by suturing together the bowel that is proximal and distal to the lesion. (B) The involved segment is removed. (C) The spur is crushed. (D) The resulting single-barreled colostomy. (E) Closure of the bowel.
FIG. Abdominoperineal resection: (A) long, lower left rectus incision; (B) both right and left leaves of peritoneum have been divided and then joined in the midline; (C) isolation of ureters, spermatic vessels and superior hemorrhoidal artery; (D) the superior hemorrhoidal artery has been ligated and divided, and the rectum is freed posteriorly to the tip of the coccyx; (E) mobilization of the rectum from its lateral attachments; (F) the sigmoid is divided between clamps; (G) the distal end of the divided sigmoid is placed deep into the pelvis. The sutured peritoneum forms the new pelvic floor.
SLIDING HERNIA Sliding hernia has been defined as the extrusion of an organ (ascending, descending or sigmoid colons) in such a way that the visceral peritoneum forms part of the sac. Therefore, attempts to isolate the sac as in indirect inguinal hernia are impossible. R. R. Graham is of the opinion that the formation of such a hernia is the result of a pushing mechanism which shoves the posterior parietal peritoneum lateral to the sigmoid so that it appears at the internal ring. As a result of this, the mesosigmoid unfolds, and the sigmoid comes to lie at the apex of the hernia. The vessels then lie behind the colonic segment and are exposed to injury if they are mistaken for adhesions and if dissection is carried in this plane. If one attempts to separate such “adhesions,” encroachment on the blood supply of the colon may result in devitalization of the bowel. Since complete reduction of the contents, high ligation of the sac and proper repair are impossible in this type of hernia, another method must be sought. Moschowitz suggested that the peritoneal cavity also be opened and the sigmoid be drawn back into it through the abdominal incision. It then is noted that the opening which has been made in the hernial sac through the inguinal incision is truly an incision in the anterior (lateral) layer of mesosigmoid. This defect is closed. Following this, no hernial sac is present. The abdominal wound is closed, and the inguinal canal is repaired by one of the routine methods.
Pancreas
EMBRYOLOGY The single adult pancreas is developed from two primitive pancreatic buds which are called the dorsal (proximal) pancreatic bud
FIG. Embryology of the pancreas. (A) The 2 primitive pancreatic buds, dorsal and ventral, before rotation has taken place. The arrow indicates the path of rotation. (B) After rotation and before fusion of the pancreatic buds. The superior mesenteric vessels (portal vein) are “sandwiched in” between the primitive buds.
and the ventral (distal) pancreatic bud. The dorsal bud springs from the posterior border of the duodenum and grows between the leaves of the dorsal mesoduodenum; its duct system empties directly into the duodenum. The ventral bud arises from the anterior border of the duodenum and invades the ventral mesoduodenum; it originates with the primitive bile duct system; hence, its duct system communicates with that of the bile. The ventral bud rotates backward behind the duodenum, around its right side, and grows back into the dorsal mesoduodenum. The two buds fuse; the ventral bud gives rise to the posterior portion of the lower part of the head and the uncinate process of the pancreas; the dorsal bud becomes the upper and the anterior part of the head, the neck, the body and the tail of the pancreas. The right side of the pancreas is directed backward, and the left side forward; the right surface is applied to the posterior abdominal wall. The peritoneum which originally covered its right side is absorbed; therefore, in the adult, the pancreas appears to be retroperitoneal, being covered by the parietal peritoneum. At the time of fusion between the ventral and the dorsal buds, a communication is established between their ducts. The duct of the dorsal bud becomes the accessory pancreatic duct of Santorini, and the duct of the ventral bud becomes the main pancreatic duct of Wirsung. In about 20 per cent of individuals the accessory duct of Santorini becomes occluded and cannot compensate for trauma inflicted on the duct of Wirsung. After rotation, the portal vein becomes “sandwiched in” between the dorsal bud which lies ventral to the vein and the ventral bud which now lies dorsal to the vein. The last statement may appear confusing at first but if it is visualized it explains the ultimate positions of the superior mesenteric and the portal veins, between the head and the neck of the pancreas. It also explains how the accessory duct, which was formerly posterior, now enters on the anterior surface of the duodenum, and the main duct, which was originally anterior, now lies posteromedial.
ADULT PANCREAS The adult pancreas is pistol-shaped. Its length, which is variable, averages from 4 to
FIG. Relations and divisions of the pancreas. The 2 projections of the pancreas, the uncinate process and the omental tuberosity, are identified.
pancreas is in contact with the renal vessels and the inferior vena cava; behind the pancreatic neck lies the portal vein. Behind the body of the pancreas, from right to left, is the aorta (with the origin of the superior mesenteric and the renal arteries), the left suprarenal gland, the left kidney and the spleen. The uncinate process (uncus hook) is a downward projection from the lower part of the head which hooks behind the superior mesenteric vessels. The omental tuberosity (tuber omentale) is another pancreatic projection which projects upward from the body. It fits into the lesser curvature of the stomach, where it comes in contact with the lesser omentum, and separates it from the downward projecting tuber omentale of the liver (left lobe).
VESSELS. Arteries. The upper border of the pancreas is a good landmark for the arteries which supply it and other organs in this region. The splenic artery passes to the left along the upper border of the body and the tail, and the hepatic artery passes to the right along the upper border of the head of the pancreas. Opposite the lower border of the duodenum the gastroduodenal artery.
FIG. The pancreas. The splenic artery passes to the left along the upper border of the body and the tail of the pancreas, and the hepatic artery passes to the right along the upper border of the neck and the head of the gland. The splenic vein lies behind the pancreas.
FIG. The 3 approaches to the pancreas: (A) through the lesser omentum; (B) through the greater omentum; (C) through the transverse mesocolon.
(hepatic) divides into a superior pancreaticoduodenal and right gastroepiploic arteries . The superior pancreaticoduodenal artery divides and continues downward between the head of the pancreas and the duodenum as 2 parallel vessels, not as a single vessel, as is usually depicted. The inferior pancreaticoduodenal (superior mesenteric) artery also divides into 2 parallel vessels which anastomose with the 2 branches of the superior pancreaticoduodenal artery. In this way 2 arterial arches are formed: one in front of the head of the pancreas and another behind it. By means of these two arches the medial aspect of the duodenum receives an anterior and posterior set of vasa recta. The head of the gland is supplied by the superior and the inferior pancreaticoduodenal arteries, and the body and the tail by the splenic artery. Veins. Pancreatic veins issue from the pancreas and end in the splenic vein. The latter passes behind the body of the pancreas and below the splenic artery. It ends behind the neck of the pancreas by joining with the superior mesenteric vein to form the portal vein. The lymphatics of the pancreas drain either directly or indirectly into the celiac glands around the root of the celiac artery.
DUCTS The pancreatic duct of Wirsung forms the chief excretory channel of the gland. It begins in the tail and passes through the middle of the gland toward its head; its termination is quite variable. In most instances, the duct opens independently into the ampulla of Vater, which then presents one opening common to both the pancreatic and the common bile ducts. In other instances, the pancreatic duct may join the common bile duct and both enter the ampulla by a common channel in another variation presents the common bile duct and the pancreatic duct enter the duodenum by entirely separate orifices. The accessory pancreatic duct of Santorini represents the original duct of the dorsal bud. In the adult it passes to the right and in front of the common bile duct. It remains patent in most instances and opens into the duodenum about % inch above the ampulla of Vater. In most individuals it anastomoses with the chief pancreatic duct (Wirsung) within the head of the pancreas.
FIG. Pancreatoduodenectomy. (A) A long right rectus incision gives ample exposure. (B) Cholecystojejunostomy may be done as a 1-stage operation or else combinedwith a radical 1-stage procedure. (C) The duodenum has been mobilized, and the gastroduodenal artery and the common duct have been severed and ligated. (D) The pylorus has been severed, and the pancreas has been incised over the superior mesenteric vessels. The jejunum has been divided immediately distal to the ligament of Treitz. (E) Following removal of the duodenum and the head of the pancreas, pancreaticojejunostomy and gastrojejunostomy complete the operation. In the 1-stage procedure it is thought preferable to anastomose the common duct to the jejunum.
SURGICAL CONSIDERATIONS
The pancreas can be considered no longer as the “hermit” organ, since it now comes within the realm of modern surgery. The approaches to the pancreas are along 3 anterior transperitoneal routes, namely, through the lesser omentum (gastrohepatic portion), the transverse mesocolon and the gastrocolic part of the greater omentum. The last-named approach is preferred, since it affords greatest exposure and does not endanger the middle colic artery; however the site and the extent of the pathology determine which route is most applicable. If, for example, a pancreatic cyst points through the lesser omentum or the transverse mesocolon, these paths are taken.
PANCREATODUODENECTOMY Pancreatoduodenectomy is done for carcinoma of the head of the pancreas, carcinoma of the ampulla of Vater and carcinoma of the lower end of the common bile duct. It may be performed in 1 or 2 stages. Whipple has done much of the pioneer work in this field. Many types of operative procedures have been described, and a typical one will be discussed here. The scope of this operation calls for a block resection of the head of the pancreas, the lower end of the common duct, the pylorus of the stomach and the entire duodenum. Hence, the gastrointestinal tract, the biliary tract and the pancreas are interrupted. The gastrointestinal tract can be restored by an end-to-side or end-to-end gastrojejunostomy. The biliary tract can be restored by an anastomosis of the common bile duct or the common hepatic duct to a portion of the gastrointestinal tract; in the 2-stage operation the gallbladder can be used for the anastomosis. Some surgeons advocate closure of the cut end of the pancreas; others prefer to anastomose it to the jejunum. Surgery is contraindicated if the portal vein or the superior mesenteric vessels are involved, if there are multiple distant metastases, or if there is invasion beyond the limits of resection. Involvement of the portal vein can be discerned by division of the gastroduodenal artery and displacement of the common duct downward. Involvement of the superior mesenteric vessels is determined by division of the gastrocolic omentum and incision of the peritoneum along the inferior border of the pancreas. If a 2-stage procedure is utilized, a cholecystojejunostomy is done first, and at the second stage this is displaced downward. The peritoneum over the right kidney is incised to the right of the duodenum, and the duodenum and the head of the pancreas are mobilized to the left. The gastrocolic omentum is divided, and the third part of the duodenum, the head of the pancreas and the superior mesenteric vessels are exposed. The gastroduodenal artery is divided and ligated; the common duct is divided, and the proximal end is invaginated. The stomach, the body of the pancreas and the jejunum are divided; the ligament of Treitz is freed. The block of tissue is removed, and the operation is completed by performing the following anastomoses: end-to-side or end-to-end gastrojejunostomy, pancreaticojejunostomy and cholecystojejunostomy (previously done in the 2-stage procedure).
SURGERY FOR PANCREATITIS Pancreatitis is still a rather obscure lesion, but the surgical procedures which have been utilized, if the case is operated on, are in the form of cholecystostomy and incision of the pancreatic capsule. This capsule is the posterior parietal peritoneum which covers the organ.
