Esophagus

The esophagus is a narrow muscular tube about 20-30 centimeters long, which starts at the pharynx at the back of the mouth, passes through the thoracic diaphragm, and ends at the cardiac orifice of the stomach. The wall of the esophagus is made up of two layers of smooth muscles, which form a continuous layer from the esophagus to the colon and contract slowly, over long periods of time. The inner layer of muscles is arranged circularly in a series of descending rings, while the outer layer is arranged longitudinally. At the top of the esophagus, is a flap of tissue called the epiglottis that closes during swallowing to prevent food from entering the trachea (windpipe). The chewed food is pushed down the esophagus to the stomach through peristaltic contraction of these muscles. It takes only about seven seconds for food to pass through the esophagus and now digestion takes place.

Stomach

The stomach is a small, ‘J’-shaped pouch with walls made of thick, distensible muscles, which stores and helps break down food. Food reduced to very small particles is more likely to be fully digested in the small intestine, and stomach churning has the effect of assisting the physical disassembly begun in the mouth. Ruminants, who are able to digest fibrous material (primarily cellulose), use fore-stomachs and repeated chewing to further the disassembly. Rabbits and some other animals pass some material through their entire digestive systems twice. Most birds ingest small stones to assist in mechanical processing in gizzards.

Food enters the stomach through the cardiac orifice where it is further broken apart and thoroughly mixed with gastric acid, pepsin and other digestive enzymes to break down proteins. The enzymes in the stomach also have an optimum conditions, meaning that they work at a specific pH and temperature better than any others. The acid itself does not break down food molecules, rather it provides an optimum pH for the reaction of the enzyme pepsin and kills many microorganisms that are ingested with the food. It can also denature proteins. This is the process of reducing polypeptide bonds and disrupting salt bridges, which in turn causes a loss of secondary, tertiary, or quaternary protein structure. The parietal cells of the stomach also secrete a glycoprotein called intrinsic factor, which enables the absorption of vitamin B-12. Mucus neck cells are present in the gastric glands of the stomach. They secrete mucus, which along with gastric juice plays an important role in lubrication and protection of the mucosal epithelium from excoriation by the highly concentrated hydrochloric acid. Other small molecules such as alcohol are absorbed in the stomach, passing through the membrane of the stomach and entering the circulatory system directly. Food in the stomach is in semi-liquid form, which upon completion is known as chyme.

After consumption of food, digestive “tonic” and peristaltic contractions begin, which helps break down the food and move it onward.[16] When the chyme reaches the opening to the duodenum known as the pylorus, contractions “squirt” the food back into the stomach through a process called retropulsion, which exerts additional force and further grinds down food into smaller particles.[16] Gastric emptying is the release of food from the stomach into the duodenum; the process is tightly controlled with liquids being emptied much more quickly than solids.[16] Gastric emptying has attracted medical interest as rapid gastric emptying is related to obesity and delayed gastric emptying syndrome is associated with diabetes mellitus, aging, and gastroesophageal reflux.[16]

The transverse section of the alimentary canal reveals four (or five, see description under mucosa) distinct and well developed layers within the stomach:

• Serous membrane, a thin layer of mesothelial cells that is the outermost wall of the stomach.

• Muscular coat, a well-developed layer of muscles used to mix ingested food, composed of three sets running in three different alignments. The outermost layer runs parallel to the vertical axis of the stomach (from top to bottom), the middle is concentric to the axis (horizontally circling the stomach cavity) and the innermost oblique layer, which is responsible for mixing and breaking down ingested food, runs diagonal to the longitudinal axis. The inner layer is unique to the stomach, all other parts of the digestive tract have only the first two layers.

• Submucosa, composed of connective tissue that links the inner muscular layer to the mucosa and contains the nerves, blood and lymph vessels.

• Mucosa is the extensively folded innermost layer. It can be divided into the epithelium, lamina propria, and the muscularis mucosae, though some consider the outermost muscularis mucosae to be a distinct layer, as it develops from the mesoderm rather than the endoderm (thus making a total of five layers). The epithelium and lamina are filled with connective tissue and covered in gastric glands that may be simple or branched tubular, and secrete mucus, hydrochloric acid, pepsinogen and rennin. The mucus lubricates the food and also prevents hydrochloric acid from acting on the walls of the stomach.

Small intestine

After being processed in the stomach, food is passed to the small intestine via the pyloric sphincter. The majority of digestion and absorption occurs here after the milky chyme enters the duodenum. Here it is further mixed with three different liquids:

• Bile, which emulsifies fats to allow absorption, neutralizes the chyme and is used to excrete waste products such as bilin and bile acids. Bile is produced by the liver and then stored in the gallbladder where it will be released to the small intestine via the bile duct. The bile in the gallbladder is much more concentrated

• Pancreatic juice made by the pancreas, which secretes enzymes such as pancreatic amylase, pancreatic lipase, and trypsinogen (inactive form of protease).

• Intestinal juice secreted by the intestinal glands in the small intestine. It contains enzymes such as enteropeptidase, erepsin, trypsin, chymotrypsin, maltase, lactase and sucrase (all three of which process only sugars).

The pH level increases in the small intestine as all three fluids are alkaline. A more basic environment causes more helpful enzymes to activate and begin to help in the breakdown of molecules such as fat globules. Small, finger-like structures called villi, and their epithelial cells is covered with numerous microvilli to improve the absorption of nutrients by increasing the surface area of the intestine and enhancing speed at which nutrients are absorbed. Blood containing the absorbed nutrients is carried away from the small intestine via the hepatic portal vein and goes to the liver for filtering, removal of toxins, and nutrient processing.

The small intestine and remainder of the digestive tract undergoes peristalsis to transport food from the stomach to the rectum and allow food to be mixed with the digestive juices and absorbed. The circular muscles and longitudinal muscles are antagonistic muscles, with one contracting as the other relaxes. When the circular muscles contract, the lumen becomes narrower and longer and the food is squeezed and pushed forward. When the longitudinal muscles contract, the circular muscles relax and the gut dilates to become wider and shorter to allow food to enter.

Large intestine

After the food has been passed through the small intestine, the food enters the large intestine. Within it, digestion is retained long enough to allow fermentation due to the action of gut bacteria, which breaks down some of the substances that remain after processing in the small intestine; some of the breakdown products are absorbed. In humans, these include most complex saccharides (at most three disaccharides are digestible in humans). In addition, in many vertebrates, the large intestine reabsorbs fluid; in a few, with desert lifestyles, this reabsorbtion makes continued existence possible.

In general, the large intestine is less vigorous in absorptive activity. It produces sacculation, renews epithelial cells, and provides protective mucus and mucosal immunity. In humans, the large intestine is roughly 1.5 meters long, with three parts: the cecum at the junction with the small intestine, the colon, and the rectum. The colon itself has four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. The large intestine absorbs water from the chyme and stores feces until it can be egested. Food products that cannot go through the villi, such as cellulose (dietary fiber), are mixed with other waste products from the body and become hard and concentrated feces. The feces is stored in the rectum for a certain period and then the stored feces is eliminated from the body due to the contraction and relaxation through the anus. The exit of this waste material is regulated by the anal sphincter.

 

ELECTROGASTROGRAPHY

The electrogastrography is a method to record the electric activity of the stomach positioning some electrodes on the skin surface of the abdominal wall. A general agreement that the electric activity of the stomach is correlated to its contractile activity exists. The target is to find a relationship between different pattern of electric activity and clinical presentation of dyspeptic disturbances.

 

Gastric Electric Activity (GEA) In vitro two major types of GEA have been recognized in the distal two/thirds of the stomach: Electrical Control Activity (ECA) and Electrical Response Activity (ERA). It has been demonstrated that intracellular electrical depolarization due to spontaneous ionic exchange through the membrane precedes contraction of the gastric smooth muscle fibers. However, not all depolarizations are followed by contractile activity and this is the main difference between gastric and cardiac muscles. Weber and Kohatsu, Kelly and Code showed as possible origin of gastric electrical activity an area of the corpus along the greater curvature where begin the longitudinal muscle fibers that continue into the duodenum. The mechanism of propagation of gastric electrical activity is still unknown but there are well definite temporal and spatial rules that regulate the propagation.

ECA is considered to be the initial rapid depolarization of the cell and is a necessary condition, even if not sufficient, so that the contraction could happen. It is periodic iature, with a period of about 20 seconds (frequency of 3 cycles per minute). Only the appearance of the plateau of the ERA, and eventually the second component of the ERA, the spikes that are superimposed over the plateau, indicate that the contraction will follow.

During the fasting state the GEA can show the patterns of the so called Migrating Myoelectrical Complex (MMC) and it can be separated into four phases: (1) quiescent phase 1, when only ECA is present; (2) transitional phase 2 when cycle of ECA are mixed with cycles in which both ECA and ERA are present; (3) phase 3 during which ECA is always followed by ERA with its two components; (4) transitional phase 4, very similar to phase 2. The total duration of the phases is 1.5-2.0 hours.

Mirizzi and Scafoglieri, Mirizzi et al have modelled the electrical field produced by the human stomach and demonstrated that the optimal position for the EGG electrodes is along the projection of the stomach axis on the abdomen wall, as shown in Figure 1.

 

Many authors have tried to use electrogastrography for clinical assessment of gastric motility disorders. Unfortunately, only qualitative methods (and therefore subjective) of evaluation of the EGG were suggested. Myntchev et al have tried to produce an objective quantitative method of evaluation of gastric electrical activity, including EGG. They demonstrated that the most reliable EGG parameter is gastric electrical frequency. It shows a good level of stability in all conditions when registered maintaining standard modalities. A further parameter that seems to be of interest is the variation of signal amplitude after meal.

The ECA (slow waves) is responsible for controlling the maximum frequency and the aboral propagation of distal gastric contractions. As reported above, the normal gastric slow waves frequency is approximately 3 cpm. Meal ingestion increases the amplitude of the EGG signal which is believed to result either from increased antral contractility or from mechanical distension of the stomach.

The more common procedure of evaluation of the electrogastrographic recording is the spectral analysis that uses the “Fast Fourier Transform” (FFT) to convert the temporal signal in its components of frequency (Figure 2). According to the theory of Fourier every periodic signal can be considered as constituted by a series of sinusoidal waves. The application of the FFT to the signal over time determines the decomposition of the signal in its components of frequency producing a spectrum of frequencies.” The amplitude of every component of frequency points out the contribution of that component in the original signal. The energy of a component of frequency is calculated as the square of the amplitude.

 

The graph obtained by the spectrum analysis shows the mean contribution of a date frequency on the whole signal expressed as energy of that frequency. The dominant mean frequency is 3.0 cpm and the corresponding energy it is express iV2. Such representation doesn’t allow following the variations of frequency and energy over time. This problem has been overcome with the introduction of the analysis Running Spectra (Figure 3). The graphic representation mostly used for the analysis Running Spectra is pseudo-three-dimensional that is able to show the variations of frequency and amplitude in the time.

Figure 3. Running Spectra analysis allows to visualize the components of gastric signal over time. From Van der Schee ET, Grashuis JT. Med Biol Eng Comput 1987; 25:57-62.

 

Clinical Application

The cutaneous registration of the electrical activity of the stomach allows to quantify the dominant frequency, the regularity of myoelectrical activity, the percentage of time in which abnormal slow or fast wave rhythms are present during fasting and postprandially, and to assess the increase in amplitude after meal (Figures 4 and 5).

Figure 4. Healthy subject. The dominant frequency in the fasting state and after the meal ingestion is 3 cpm.

 

Figure 5. Healthy subject. Normal increase of the gastric signal after meal ingestion with dominant 3 cpm frequency.

 

Using the same terminology of the electrocardiography it is possible to describe the gastric dysrhythmias as tachygastria and bradigastria. Normally the 3 cpm frequency represents the 70% of the recorded cycles. When this percentage is reduced the electrical activity of the stomach is altered. The tachygastria and the bradigastria and the abnormal low amplitude of the signal after meal ingestion have been defined in patients with idiopathic or diabetic gastroparesis (Figure 6). Camilleri et al described also abnormalities in patients with unexplained nausea and vomiting, motion sickness, and nausea and vomiting of pregnancy.

Figure 6. Diabetic not compensated patient with dominant bradigastria before meal. After meal ingestion irregular increase of frequency of the gastric electric activity.

 

 

Parkman et al showed EGG abnormalities in 75% of patients with gastroparesis versus 25% of symptomatic patients with normal gastric emptying. EGG abnormalities and delayed gastric emptying may define different patient populations with dyspeptic symptoms (Figures 7 and 8). Koch et al showed that the symptomatic response to antiemetic or prokinetic drug treatments correlated better with resolution of gastric dysrhythmias than acceleration of delayed emptying in some groups of patients. Even hyperglycaemia may provoke dysrhythmias in diabetic patients.

 

Figure 7. Patient with unexplained nausea. Dysrhythmia is evident before meal. The normal 3 cpm appears after the ingestion of foods.

 

 

Figure 8. Patient with unexplained nausea. Amplitude increment of the signal with dominant 3 cpm frequency after meal ingestion.

 

In clinical practice EGG has been used to demonstrate gastric myoelectrical abnormalities in patients with unexplained nausea and vomiting or functional dyspepsia. It seems correct to consider the EGG, joined to scintigraphy, as a tool of a general evaluation of patients with symptoms suggestive of an upper gastrointestinal motility disorder . To date there have been little investigation to demonstrate the utility of EGG in the management of patients with suspected gastric motility abnormalities.

 

Perspective

Gastric emptying scintigraphy of a solidphase meal is considered the gold standard for the study of gastroparesis. Breath test using the non radioactive isotope C bound to digestible substance have been validated for measuring gastric emptying. Most commonly, C-labeled octanoate, a medium chain triglyceride, is bound into a solid meal (eggs with ham, butter, bread). After ingestion and stomach emptying, C-octanoate is absorbed in the small intestine and metabolized to CO2, which is then expelled from the lungs. The limiting step is the rate of gastric emptying. Octanoate breath testing provide a measure of solid phase emptying and its results are reproducible and correlate with findings on gastric emptying scintigraphy . C breath test do not use ionizing radiation and can be used to test patients in the community or even at the bedside where the gamma camera facilities are not available. Breath samples can be preserved and shipped to a laboratory for analysis by means a mass spectrometer. This possibility can make easy to perform a double test: EGG registration while the person is eating a C-octanoate meal allowing to elaborate a correlation between electric gastric activity and gastric mechanical activity in different subsets of dyspeptic patients for search use or, may be, for clinical use. EGG could make its first steps towards reliable clinical applications.

Electrogastrography has the potential to become a routine clinical procedure in the near future.

 

COLONOSCOPY

 

Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis (e.g. ulceration, polyps) and grants the opportunity for biopsy or removal of suspected lesions.

Colonoscopy can remove polyps as small as one millimetre or less. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not.

Colonoscopy is similar to, but not the same as, sigmoidoscopy—the difference being related to which parts of the colon each can examine. A colonoscopy allows an examination of the entire colon (measuring four to five feet in length). A sigmoidoscopy allows an examination of the distal portion (final two feet) of the colon, which may be sufficient because benefits to colonoscopy (cancer survival) have been limited to the distal portion of the colon.

The American Cancer Society “Guidelines for the Early Detection of Cancer” recommend, beginning at age 50, both men and women follow one of these testing schedules for screening to find colon polyps and cancer: 1. Flexible sigmoidoscopy every 5 years, or 2. Colonoscopy every 10 years, or 3. Double-contrast barium enema every 5 years, or 4. CT colonography (virtual colonoscopy) every 5 years.

A sigmoidoscopy is often used as a screening procedure for a full colonoscopy, often done in conjunction with a fecal occult blood test (FOBT). About 5% of these screened patients are referred to colonoscopy.^{http://en.wikipedia.org/wiki/Colonoscopy – cite_note-4#cite_note-4}

Virtual colonoscopy, which uses 2D and 3D imagery reconstructed from computed tomography (CT) scans or from nuclear magnetic resonance (MR) scans, is also possible, as a totally non-invasive medical test, although it is not standard and still under investigation regarding its diagnostic abilities. Furthermore, virtual colonoscopy does not allow for therapeutic maneuvers such as polyp/tumour removal or biopsy nor visualization of lesions smaller than 5 millimetres. If a growth or polyp is detected using CT colonography, a standard colonoscopy would still need to be performed.

Colonoscopy is not recommended for patients having an active flare of ulcerative colitis or Crohn’s disease to avoid a perforation of the colon. Additionally, surgeons have lately been using the term pouchoscopy to refer to a colonoscopy of the ileo-anal pouch.

Medical uses

Conditions that call for colonoscopies include gastrointestinal hemorrhage, unexplained changes in bowel habit and suspicion of malignancy. Colonoscopies are often used to diagnose colon cancer, but are also frequently used to diagnose inflammatory bowel disease. In older patients (sometimes even younger ones) an unexplained drop in hematocrit (one sign of anemia) is an indication that calls for a colonoscopy, usually along with an esophagogastroduodenoscopy (EGD), even if no obvious blood has been seen in the stool (feces).

Fecal occult blood is a quick test which can be done to test for microscopic traces of blood in the stool. A positive test is almost always an indication to do a colonoscopy. In most cases the positive result is just due to hemorrhoids; however, it can also be due to diverticulosis, inflammatory bowel disease (Crohn’s disease, ulcerative colitis), colon cancer, or polyps. However—since its development by Dr. Hiromi Shinya and Dr. William I. Wolff in the 1960s—polypectomy has become a routine part of colonoscopy, allowing for quick and simple removal of polyps without invasive surgery.

Colonoscopy has become a primary routine screening test for people in the US who are over 50 years of age, but flexible sigmoidoscopy every 5 years, or colonoscopy every 10 years, or double-contrast barium enema every 5 years, or CT colonography (virtual colonoscopy) every 5 years are all equally recommended.; Subsequent rescreenings are then scheduled based on the initial results found, with a five- or ten-year recall being common for colonoscopies that produce normal results.^{http://en.wikipedia.org/wiki/Colonoscopy – cite_note-7#cite_note-7} Patients with a family history of colon cancer are often first screened during their teenage years. Among people who have had an initial colonoscopy that found no polyps, the risk of developing colorectal cancer within five years is extremely low. Therefore, there is no need for those people to have another colonoscopy sooner than five years after the first screening.

Procedure

Preparation

The colon must be free of solid matter for the test to be performed properly. For one to three days, the patient is required to follow a low fiber or clear-liquid only diet. Examples of clear fluids are apple juice, chicken and/or beef broth or bouillon, lemon-lime soda, lemonade, sports drink, and water. It is very important that the patient remain hydrated. Sports drinks contain electrolytes which are depleted during the purging of the bowel. Orange juice, prune juice, and milk containing fiber should not be consumed, nor should liquids dyed red, purple, orange, or sometimes brown; however, cola is allowed. In most cases, tea (no milk) or black coffee (no milk) are allowed.

The day before the colonoscopy, the patient is either given a laxative preparation (such as Picosalax, Bisacodyl, phospho soda, sodium picosulfate, or sodium phosphate and/or magnesium citrate) and large quantities of fluid, or whole bowel irrigation is performed using a solution of polyethylene glycol and electrolytes. Often, the procedure involves both a pill-form laxative and a bowel irrigation preparation with the polyethylene glycol powder dissolved into any clear liquid, preferably a sports drink which contain electrolytes.

In this case, a typical procedure regimen then would be as follows: in the morning of the day before the procedure, a 238 g bottle of polyethylene glycol powder should be poured into 64 oz. of the chosen clear liquid, which then should be mixed and refrigerated. Two (2) bisacodyl 5 mg tablets are taken 3 pm; at 5 pm, the patient starts drinking the mixture (approx. 8 oz. each 15-30 min. until finished); at 8 pm, take two (2) bisacodyl 5 mg tablets; continue drinking/hydrating into the evening until bedtime with clear permitted fluids. A common brand name of bisacodyl is Dulcolax, and store brands are available. A common brand name of polyethylene glycol powder is MiraLAX. It may be advisable to schedule the procedure early on a given day so the patient need not go without food and only limited fluids the morning of the procedure on top of having to go through the foregoing preparation procedures the preceding day.

Since the goal of the preparation is to clear the colon of solid matter, the patient should plan to spend the day at home in comfortable surroundings with ready access to toilet facilities. The patient may also want to have at hand moist towelettes or a bidet for cleaning the anus. A soothing salve such as petroleum jelly applied after cleaning the anus will improve patient comfort.

The patient may be asked to skip aspirin and aspirin-like products such as salicylate, ibuprofen, and similar medications for up to ten days before the procedure to avoid the risk of bleeding if a polypectomy is performed during the procedure. A blood test may be performed before the procedure.

Investigation

During the procedure the patient is often given sedation intravenously, employing agents such as fentanyl or midazolam. Although meperidine (Demerol) may be used as an alternative to fentanyl, the concern of seizures has relegated this agent to second choice for sedation behind the combination of fentanyl and midazolam. The average person will receive a combination of these two drugs, usually between 25 to 100 µg IV fentanyl and 1–4 mg IV midazolam. Sedation practices vary between practitioners and nations; in some clinics in Norway, sedation is rarely administered.

Some endoscopists are experimenting with, or routinely use, alternative or additional methods such as nitrous oxide and propofol, which have advantages and disadvantages relating to recovery time (particularly the duration of amnesia after the procedure is complete), patient experience, and the degree of supervisioeeded for safe administration. This sedation is called “twilight anesthesia.” For some patients it is not fully effective, so they are indeed awake for the procedure and can watch the inside of their colon on the colour monitor. Substituting propofol for midazolam, which gives the patient quicker recovery, is gaining wider use, but requires closer monitoring of respiration.

A meta-analysis found that playing music improves patient tolerability of the procedure.http://en.wikipedia.org/wiki/Colonoscopy – cite_note-18#cite_note-18

The first step is usually a digital rectal examination, to examine the tone of the sphincter and to determine if preparation has been adequate. The endoscope is then passed through the anus up the rectum, the colon (sigmoid, descending, transverse and ascending colon, the cecum), and ultimately the terminal ileum. The endoscope has a movable tip and multiple channels for instrumentation, air, suction and light. The bowel is occasionally insufflated with air to maximize visibility (a procedure which gives one the false sensation of needing to take a bowel movement).[20] Biopsies are frequently taken for histology. Additionally in a procedure known as “Chromoscopy”, a contrast-dye (such as Indigo carmine) may be sprayed via the endoscope onto the bowel wall to help visualise any abnormalities in the mucosal morphology.

In most experienced hands, the endoscope is advanced to the junction of where the colon and small bowel join up (cecum) in under 10 minutes in 95% of cases. Due to tight turns and redundancy in areas of the colon that are not “fixed”, loops may form in which advancement of the endoscope creates a “bowing” effect that causes the tip to actually retract. These loops often result in discomfort due to stretching of the colon and its associated mesentery. Manoeuvres to “reduce” or remove the loop include pulling the endoscope backwards while torquing the instrument. Alternatively, body position changes and abdominal support from external hand pressure can often “straighten” the endoscope to allow the scope to move forward. In a minority of patients, looping is often cited as a cause for an incomplete examination. Usage of alternative instruments leading to completion of the examination has been investigated, including use of pediatric colonoscope, push enteroscope and upper GI endoscope variants.^[

For screening purposes, a closer visual inspection is then often performed upon withdrawal of the endoscope over the course of 20 to 25 minutes. Lawsuits over missed cancerous lesions have recently prompted some institutions to better document withdrawal time as rapid withdrawal times may be a source of potential medical legal liability. This is often a real concern in clinical settings where high caseloads could provide financial incentive to complete colonoscopies as quickly as possible.

Suspicious lesions may be cauterized, treated with laser light or cut with an electric wire for purposes of biopsy or complete removal polypectomy. Medication can be injected, e.g. to control bleeding lesions. On average, the procedure takes 20–30 minutes, depending on the indication and findings. With multiple polypectomies or biopsies, procedure times may be longer. As mentioned above, anatomic considerations may also affect procedure times.

After the procedure, some recovery time is usually allowed to let the sedative wear off. Outpatient recovery time can take an estimate of 30–60 minutes. Most facilities require that patients have a person with them to help them home afterwards (again, depending on the sedation method used).

One very common aftereffect from the procedure is a bout of flatulence and minor wind pain caused by air insufflation into the colon during the procedure.

An advantage of colonoscopy over x-ray imaging or other, less invasive tests, is the ability to perform therapeutic interventions during the test. A polyp is a growth of excess of tissue that can develop into cancer. If a polyp is found, for example, it can be removed by one of several techniques. A snare device can be placed around a polyp for removal. Even if the polyp is flat on the surface it can often be removed. For example, the following shows a polyp removed in stages:

·                   

Polyp is identified

·                   

A sterile solution is injected under the polyp to lift it away from deeper tissues.

·                   

A portion of the polyp is now removed.

·                   

The polyp is fully removed.

Pain Management

The pain associated with the procedure is not caused by the insertion of the scope but rather by the inflation of the colon in order to do the inspection. The scope itself is essentially a long, flexible tube about a centimetre in diameter, i.e. as big around as the little finger, which is less than the diameter of an average stool.

The colon is wrinkled and corrugated, somewhat like an accordion or a clothes-dryer exhaust tube, which gives it the large surface area needed for digestion. In order to inspect this surface thoroughly the physician blows it up like a balloon, using an air compressor, in order to get the creases out. The stomach, intestines and colon have a so-called “second brain” wrapped around them, which autonomously runs the chemical factory of digestion. It uses complex hormone signals and nerve signals to communicate with the brain and the rest of the body. Normally a colon’s job is to digest food and regulate the intestinal flora. The harmful bacteria in rancid food, for example, creates gas. The colon has distension sensors that can tell when there is unexpected gas pushing the colon walls out —thus the “second brain” tells the person that he or she is having intestinal difficulties by way of the sensation of nausea. Doctors typically recommend either total anaesthesia or a partial “twilight” sedative to either preclude or to lessen the patient’s awareness of pain or discomfort, or just the unusual sensations of the procedure. Once the colon has been inflated, the doctor inspects it with the scope as it is slowly pulled backwards. If any polyps are found they are then cut out for later biopsy.

Some doctors prefer to work with totally anesthetized patients inasmuch as the lack of any perceived pain or discomfort allows for a leisurely examination. Twilight sedation is, however, inherently safer than general anesthesia; it also allows the patients to follow simple commands and even to watch the procedure on a closed-circuit monitor. For these reasons it is generally best to request twilight sedation and ask the doctor to take his or her time despite any discomfort which the procedure may entail. Tens of millions of adults annually need to have colonoscopies, and yet many don’t because of concerns about the procedure.

It is worth noting that in many hospitals (for instance St. Mark’s Hospital, London, which specialises in intestinal and colorectal medicine) colonoscopies are carried out without any sedation.] This allows the patient to shift his or her body position to help the doctor carry out the procedure and significantly reduces recovery time and side-effects. Although there is some discomfort when the colon is distended with air, this is not usually particularly painful and it passes relatively quickly. Patients can then be released from hospital on their own very swiftly without any feelings of nausea.

Capsule endoscopy

 

 Capsule endoscopy is a way to record images of the digestive tract for use in medicine. The capsule is the size and shape of a pill and contains a tiny camera. After a patient swallows the capsule, it takes pictures of the inside of the gastrointestinal tract. The primary use of capsule endoscopy is to examine areas of the small intestine that cannot be seen by other types of endoscopy such as colonoscopy or esophagogastroduodenoscopy (EGD). This type of examination is often done to find sources of bleeding or abdominal pain. The procedure was approved by the U.S. Food and Drug Administration (FDA) in 2001.

 

Capsule endoscopy is used to examine parts of the gastrointestinal tract that cannot be seen with other types of endoscopy. Upper endoscopy, also called EGD, uses a camera attached to a long flexible tube to view the esophagus, the stomach and the beginning of the first part of the small intestine called the duodenum. A colonoscope, inserted through the rectum, can view the colon and the distal portion of the small intestine, the terminal ileum. Unfortunately, these two types of endoscopy cannot visualize the majority of the middle portion of the gastrointestinal tract, the small intestine. Capsule endoscopy is useful when disease is suspected in the small intestine and can sometimes diagnose sources of occult bleeding [blood visible microscopically only] or causes of abdominal pain such as Crohn’s disease, or peptic ulcers. Capsule endoscopy can be used to diagnose problems in the small intestine, but unlike EGD or colonoscopy, cannot treat pathology that may be discovered. The capsule endoscopy can use bluetooth to transfer the captured images. A transmitted radio frequency signal can be used to accurately estimate the location of the capsule and to track it in real-time inside the body and gastrointestinal tract

Capsule Endoscopy lets your doctor examine the lining of the middle part of your gastrointestinal tract, which includes the three portions of the small intestine (duodenum, jejunum, ileum). Your doctor will give you a pill sized video camera for you to swallow. This camera has its own light source and takes pictures of your small intestine as it passes through. These pictures are sent to a small recording device you have to wear on your body. 

Your doctor will be able to view these pictures at a later time and might be able to provide you with useful information regarding your small intestine.

Why is Capsule Endoscopy Done?

Capsule endoscopy helps your doctor evaluate the small intestine. This part of the bowel cannot be reached by traditional upper endoscopy or by colonoscopy. The most common reason for doing capsule endoscopy is to search for a cause of bleeding from the small intestine. It may also be useful for detecting polyps, inflammatory bowel disease (Crohn’s disease), ulcers, and tumors of the small intestine.

As is the case with most new diagnostic procedures, not all insurance companies are currently reimbursing for this procedure. You may need to check with your own insurance company to ensure that this is a covered benefit.

How Should I Prepare for the Procedure?

An empty stomach allows for the best and safest examination, so you should have nothing to eat or drink, including water, for approximately twelve hours before the examination. Your doctor will tell you when to start fasting.

Tell your doctor in advance about any medications you take including iron, aspirin, bismuth subsalicylate products and other over-the-counter medications. You might need to adjust your usual dose prior to the examination.

 

Discuss any allergies to medications as well as medical conditions, such as swallowing disorders and heart or lung disease.

 

Tell your doctor of the presence of a pacemaker or defibrillator, previous abdominal surgery, or previous history of bowel obstructions in the bowel, inflammatory bowel disease, or adhesions.

Your doctor may ask you to do a bowel prep/cleansing prior to the examination.

What Can I Expect During Capsule Endoscopy?

Your doctor will prepare you for the examination by applying a sensor device to your abdomen with adhesive sleeves (similar to tape). The pill-sized capsule endoscope is swallowed and passes naturally through your digestive tract while transmitting video images to a data recorder worn on your belt for approximately eight hours. At the end of the procedure you will return to the office and the data recorder is removed so that images of your small bowel can be put on a computer screen for physician review.

Most patients consider the test comfortable. The capsule endoscope is about the size of a large pill. After ingesting the capsule and until it is excreted you should not be near an MRI device or schedule an MRI examination.

What Happens After Capsule Endoscopy?

 

You will be able to drink clear liquids after two hours and eat a light meal after four hours following the capsule ingestion, unless your doctor instructs you otherwise. You will have to avoid vigorous physical activity such as running or jumping during the study. Your doctor generally can tell you the test results within the week following the procedure; however, the results of some tests might take longer.

What are the Possible Complications of Capsule Endoscopy?

 

Although complications can occur, they are rare when doctors who are specially trained and experienced in this procedure perform the test. There is potential for the capsule to be stuck at a narrowed spot in the digestive tract resulting in bowel obsctruction. This usually relates to a stricture (narrowing) of the digestive tract from inflammation, prior surgery, or tumor. It’s important to recognize obstruction early. Signs of obstruction include unusual bloating, abdominal pain, nausea or vomiting. You should call your doctor immediately for any such concerns. Also, if you develop a fever after the test, have trouble swallowing or experience chest pain, tell your doctor immediately. Be careful not to prematurely disconnect the system as this may result in loss of pictures being sent to your recording device.

Capsule endoscopy may also be called:

• capsule enteroscopy

• wireless capsule endoscopy

Capsule endoscopy allows for examination of the small intestine, which cannot be easily reached by traditional methods of endoscopy.

 

a,b, Gastric folds in the body of the stomach; c,d, villous pattern of the small bowel enhanced by the presence of a little water and an air bubble in the lumen; e,f, airless images of normal jejunum, viewed with the lumen closed in front of the optical dome of the capsule; g,h, views of the terminal ileum.

 

 

ULTRASOUND

Duodenography and colonography are performed like a standard abdominal examination using B-mode and color flow Doppler ultrasonography using a low frequency transducer — for example a 2.5 MHz — and a high frequency transducer, for example a 7.5 MHz probe. Detailed examination of duodenal walls and folds, colonic walls and haustra was performed using a 7.5 MHz probe. Deeply located abdominal structures were examined using 2.5 MHz probe. All ultrasound examinations are performed after overnight fasting (for at least 16 hours) using standard scanning procedure. Subjects are examined with and without water contrast. Water contrast imaging is performed by having adult subjects take at least one liter of water prior to examination. Patients are examined in the supine, left posterior oblique, and left lateral decubitus positions using the intercostal and subcostal approaches. The liver, gall bladder, spleen, pancreas, duodenum, colon, and kidneys are routinely evaluated in all patients. With patient lying supine, the examination of the duodenum with high frequency ultrasound duodenography is performed with 7.5 MHz probe placed in the right upper abdomen, and central epigastric successively; for high frequency ultrasound colonography, the ascending colon, is examined with starting point usually midway of an imaginary line running from the iliac crest to the umbilicus and proceeding cephalid through the right mid abdomen; for the descending colon, the examination begins from the left upper abdomen proceeding caudally and traversing the left mid abdomen and left lower abdomen, terminating at the sigmoid colon in the lower pelvic region. Color flow Doppler sonography is used to examine the localization of lesions in relation to vessels. All measurements of diameter and wall thickness are performed with built-in software. Measurements are taken between peristaltic waves.^{http://en.wikipedia.org/wiki/Colonoscopy – cite_note-24#cite_note-24}

·                   

The abdominal regions scanned in the order.

·                   

The duodenal tri-band wall with folds of Kerckring, showing floaters with water contrast.

·                   

A high resolution view of colonic haustration.

Results

A 2009 study published in the Annals of Internal Medicine implies that colonoscopy screening prevents approximately two thirds of the deaths due to colorectal cancers on the left side of the colon, and is not associated with a significant reduction in deaths from right-sided disease.http://en.wikipedia.org/wiki/Colonoscopy – cite_note-25#cite_note-25 This study examined people with colon cancer diagnosed between 1996 and 2001 in Ontario who died of colon cancer by 2003, and hence studied colonoscopies done in the early to mid 1990s. (Since the procedure continues to evolve, more recent colonoscopies may be more effective). The summary result, according to table 3 of the report, show approximately a 37% reduction in the death rate from colorectal cancer, with a significantly lower reduction in death for “incomplete” colonoscopies.

A 2011 study published in Annals of Internal Medicine, on the other hand, showed that in people who had colonoscopy in the previous 10 years “the risks for early and more advanced stages of cancer were reduced by more than 50%. A lower risk for CRC [colorectal cancer] was seen for both cancer on the left side of the colon (closer to the anus and thus easier to reach during colonoscopy) and for cancer on the right side (which is harder to reach).”

Risks

This procedure has a low (0.35%) risk of serious complications. In a 2006 study of colonoscopies done from 1994 to 2002, Levin et al., found serious complications occurred in 5.0 of 1000 colonoscopies,^[ comprising 0.8 in 1000 colonoscopies without biopsy or polypectomy, and a rate of 7.0 per 1000 for colonoscopies with biopsy or polypectomy; although McDonell and Loura criticize this rate as being unacceptably high.

The rate of complications varies with the practitioner and institution performing the procedure, as well as a function of other variables.

The most serious complication generally is the gastrointestinal perforation, which is life-threatening and requires immediate major surgery for repair. A 2003 summary study of 25,000 patients showed a perforation rate of 0.2%, and a death rate of 0.006% on a total of 84,000 patients. The 2006 study by Levin et al. showed a perforation rate of 0.09%;^{http://en.wikipedia.org/wiki/Colonoscopy – cite_note-Levin2006-29#cite_note-Levin2006-29} while a 2009 study quoted a similar perforation rate of 0.082%. Appendicitis, has been associated with either perforation or colonoscopy, in case reports in Korean, Italian and English journals.

According to a study published in the Annals of Internal Medicine,^{http://en.wikipedia.org/wiki/Wikipedia:Citation_needed} for which researchers reviewed colon cancer screening data from 1966 to 2001, the most severe complications from colonoscopy are perforation (that occurred in 0.029% to 0.72% of cases), heavy bleeding (occurring in 0.2% to 2.67 % of colonoscopies) and death (occurring in 0.003% to 0.03% of colonoscopy patients).^[

An analysis of the relative risks of sigmoidoscopy and colonoscopy, published in the February 5, 2003 issue of the Journal of the National Cancer Institute brought into attention that the risk of perforation after colonoscopy is approximately double that after sigmoidoscopy (consistent with the fact that colonoscopy examines a longer section of the colon), even though this difference appeared to be decreasing.

Bleeding complications may be treated immediately during the procedure by cauterization via the instrument. Delayed bleeding may also occur at the site of polyp removal up to a week after the procedure and a repeat procedure can then be performed to treat the bleeding site. Even more rarely, splenic rupture can occur after colonoscopy because of adhesions between the colon and the spleen.

As with any procedure involving anaesthesia, other complications would include cardiopulmonary complications such as a temporary drop in blood pressure, and oxygen saturation usually the result of overmedication, and are easily reversed. Anesthesia can also increase the risk of developing blood clots and lead to pulmonary embolism or deep venous thrombosis. (DVT) In rare cases, more serious cardiopulmonary events such as a heart attack, stroke, or even death may occur; these are extremely rare except in critically ill patients with multiple risk factors. In very rare cases, coma associated with anesthesia may occur.

Virtual colonoscopies carry risks that are associated with radiation exposure.

Severe dehydration caused by the laxatives that are usually administered during the bowel preparation for colonoscopy also may occur. Therefore, patients must drink large amounts of fluids during the days of colonoscopy preparation to prevent dehydration. Loss of electrolytes or dehydration is potential risk that can even prove deadly. In rare cases, severe dehydration can lead to kidney damage or renal dysfunction under the form of phosphate nephropathy.http://en.wikipedia.org/wiki/Colonoscopy – cite_note-pmid18797448-35#cite_note-pmid18797448-35

Colonoscopy preparation and colonoscopy procedure can cause inflammation of the bowels and diarrhea or even bowel obstruction.

During colonoscopies where a polyp is removed (a polypectomy), the risk of complications has been higher, although still very uncommon, at about 2.3 percent. One of the most serious complications that may arise after colonoscopy is the postpolypectomy syndrome. This syndrome occurs due to potential burns to the bowel wall when the polyp is removed. It is however a very rare complication and as a result patients may experience fever and abdominal pain. The condition is treated with intravenous fluids and antibiotics while the patient is recommended to rest.

Bowel infections are a potential colonoscopy risk, although very rare. The colon is not a sterile environment as many bacteria live in the colon to assure the well-functioning of the bowel and therefore the risk of infections is very low. Infections can occur during biopsies when too much tissue is removed and bacteria protrude in areas they do not belong to or in cases when the lining of the colon is perforated and the bacteria get into the abdominal cavity. Infection may also be transmitted between patients if the colonoscope is not cleaned and sterilized properly between tests, although the risk of this happening is very low.

Minor colonoscopy risks may include nausea, vomiting or allergies to the sedatives that are used. If medication is given intravenously, the vein may become irritated. Most localized irritations to the vein leave a tender lump lasting a number of days but going away eventually. The incidence of these complications is less than 1%.

On very rare occasions, intracolonic explosion may occur. High frequency ultrasound duodenography and colonography do not carry the risks associated with a traditional colonoscopy.^]

Although complications after colonoscopy are uncommon, it is important for patients to recognize early signs of any possible complications. They include severe abdominal pain, fevers and chills, or rectal bleeding (more than half a cup).

Controversy

Colonoscopy reduces cancer rates by preventing some colon cancers on the left side of the colon; these colon polyps and early cancers would have been treated during a safer sigmoidoscopy procedure. Colonoscopy is relatively risky, with 5 in 1000 patients facing serious complications. To prevent one cancer death, 1,250 colonoscopies need to be performed, but perforation of the colon occurs at a rate of about 1 in 1000 procedures.

Since polyps often take 10 to 15 years to transform into cancer, in someone at average risk of colorectal cancer, guidelines recommend 10 years after a normal screening colonoscopy before the next colonoscopy. (This interval does not apply to people at high risk of colorectal cancer, or to those who experience symptoms of colorectal cancer.)

Colonoscopy is not recommended for patients over 75, and the procedure has been “considerably overused” among elderly patients. Researchers found that older patients with three or more significant health problems, like dementia or heart failure, had high rates of repeat colonoscopies without medical indications. These patients are less likely to live long enough to develop colon cancer. Gordon states, “At about $1,000 per procedure, there’s clearly an economic incentive”.

 

pH-metry

It is during the catabolic process when the acid or alkaline ash is produced. During every step of the metabolic pathway the body is constantly adjusting its pH.

When you drink or eat any substance; it has a natural pH value that may be acidic, neutral, or alkaline. As soon as the food or liquid enter our stomach is empties into a pool of gastric juice, principally of hydrochloric acid and some enzymes etc… At this point the highly acidic environment now changes the pH of what was ingested into an acidic pH. Our stomach lining contains cells that monitor the pH. If it begins to become more alkaline, goblet cells pump acid into the stomach to bring the stomachs environment to the correct pH necessary for proper digestion, so high alkaline water is totally changed by the stomach acid. Once the broken down food is ready to leave he stomach, it is squirted a little at a time into our small intestine where the small intestines sensory cells sense a very dangerous acid substance and signal the pancreas to squirt bicarbonate into the intestine to neutralize the pH once again. Alkaline water does not make our bodies more alkaline or more acidic. It’s not this simple, there are many steps in between, but I think you get the picture.

 24 HOUR PH MONITOR (ESOPHAGEAL PH)

 

A 24 hour pH Monitor test measures how often stomach acid flows into the lower esophagus and the degree of acidity during a 24 hour period.

Equipment

A small thin probe at the end of a long tube is the equipment used for measuring esophageal pH. This probe can measure the acidity of the patient’s stomach. The probe is gently inserted through the nose down to the end of the esophagus. A portable recorder is attached and is carried at the waist. The acidity in the lower esophagus is recorded on a paper tape during a 24 hour period. When the patient experiences reflux or other symptoms he or she presses a button on the recorder to mark the time. This will show how the acidity level relates to the patient’s activity. After the probe is removed the recording is analyzed and a full report is sent back to the physician.

Reason for the Exam

Symptoms such as heartburn, difficulty swallowing food or liquid and chest pain are most common reasons for performing a 24 Hour pH Monitor. The measurement of pH may be helpful in determining the success of treatment for acid reflux. Therefore, this procedure is often done before and after medical and surgical treatment of acid reflux disease.

Preparation

The patient should fast 8 hours before the procedure, This includes food and liquids. Patients need to review all medications they are taking with their physician so they can be advised which they should and should not take before the test. Many medications need to be stopped 48 hours before the test. These include:

·                    Caffiene (coffee, tea, cola, chocolate)

·                    Alcohol

·                    Propulsid

·                    Reglan

·                    Urecholine

·                    Erythromycin

·                    Nitroglycerine

·                    Calcium Channel Blockers (Procardia, Adalat, Calan, Cardizem, etc.)

·                    Beta Blockers (Corgard, Inderal, Lopressor, etc.)

·                    Donnatol

·                    Librax

·                    Levsin

·                    Tagasmet

·                    Zantac

·                    Pepcid

·                    Axid

·                    Prilosec

·                    Prevacid

Again, please be sure to review all medications with your physician prior to your appointment as there may be other medicines that need to be stopped that are not listed above.

The Procedure

The procedure takes 10 to 15 minutes from start to finish. While the patient is seated or lying on their side a thin soft tube is gently inserted through the nose. The patient is asked to swallow so the tip of the tube enters the esophagus and the technician quickly passes the tube to the desired level. There may be some slight gagging at this point but it is easily controlled. The tubing is then attached to the recorder and attached to the waist. The patient is discharged to his or her regular diet and activities.

Benefits and Alternatives

The clear documentation of the degree and duration of the acidity in the esophagus is the primary benefit of this exam. A specific treatment program can be outlined or reassurance given if the exam is normal.

Nothing really takes the place of the 24 Hour pH Measurement, but often this exam is performed in association with a pressure recording of the esophagus called an Esophageal Manometry.

Side Effects and Complications

Generally there are no serious complications associated with the Esophageal pH test.

Table.

Functional pH range of the stomach

 

Summary

The 24 hour pH test is a valuable tool used to determine the severity of acid reflux into the esophagus. With this information the physician can usually develop effective treatment for most patients who have acid disorders in the lower esophagus.

 

Gastrointestinal Telemetry

a method of examining the functioning of the gastrointestinal system by means of radio

Figure 1. Diagram illustrating the operating principle of a radio telemetry system for examining the functions of the gastrointestinal tract: (1) endoradiosonde in the stomach, (2) receiving antenna, (3) radio receiver, (4) monitor

telemetry. In gastrointestinal telemetry, a patient swallows a miniature radio transmitter, or endoradiosonde, which generates electromagnetic oscillations. As the endoradiosonde passes through the gastrointestinal tract, effects of physiological, physical, and chemical phenomena give rise to frequency modulation of the oscillations, which are detected by a radio receiver (Figure 1).

The oscillators of endoradiosondes operate in the frequency band from 300 to 450 kilohertz (kHz) or from 1,800 to 2,000 kHz. Endoradiosondes for the determination of temperature, pressure, or pH are manufactured (Figure 2).

Figure 2. The external appearance of endoradiosondes for the examination of: (1) temperature, (2) pressure, and (3) pH; a one-kopek coin is shown for size comparison

The movement of an endoradiosonde makes it possible to observe processes that occur in all divisions of the gastrointestinal tract. A thread is sometimes attached to an endoradiosonde; the thread inhibits the movement of the device, for example, from the stomach to the duodenum. The location of an endoradiosonde is determined by means of fluoroscopy or radio direction finding.

Gastrointestinal telemetry does not disturb normal digestive processes.

Manometry

Manometry is measurement of pressure within various parts of the GI tract. It is done by passing a catheter containing solid-state or liquid-filled pressure transducers through the mouth or anus into the lumen of the organ to be studied. Manometry typically is done to evaluate motility disorders in patients in whom structural lesions have been ruled out by other studies. Manometry is used in the esophagus, stomach and duodenum, sphincter of Oddi, and rectum. Aside from minor discomfort, complications are very rare. Patients must have nothing by mouth (npo) after midnight.

Esophageal manometry:

This test is used to evaluate patients with dysphagia, heartburn, regurgitation, or chest pain. It measures the pressure in the upper and lower esophageal sphincters, determines the effectiveness and coordination of propulsive movements, and detects abnormal contractions.

Manometry can be used to diagnose esophageal motility disorders such as achalasia, diffuse spasm, systemic sclerosis, and lower esophageal sphincter hypotension and hypertension. It also is used to evaluate esophageal function and anatomy such as hiatus hernia before certain therapeutic procedures (eg, antireflux surgery, pneumatic dilation for achalasia). Newer high-resolution manometry is often combined with impedance testing to simultaneously evaluate bolus transit through the esophagus during the test swallows.

 

Gastroduodenal manometry:

In this test, transducers are placed in the gastric antrum, duodenum, and proximal jejunum. Pressure is monitored for 5 to 24 h in both fasting and fed states. This test is usually used in patients who have symptoms suggestive of dysmotility but have normal gastric emptying study results or who are unresponsive to therapy. It can help determine whether the patient’s symptoms or dysmotility result from a muscular disorder (abnormal contraction amplitude but normal pattern) or nerve disorder (irregular contraction pattern but normal amplitude).

 

Barostat:

This is a pressure-sensing device that is placed in the stomach to measure gastric accommodation. The device consists of a plastic balloon and an electronic controller that varies the amount of air in the balloon to maintain constant pressure. This device is used mainly in research studies assessing sensory threshold and altered visceral perception, particularly in functional GI disorders.

 

Anorectal manometry:

In this test, a pressure transducer is placed in the anus to evaluate the anorectal sphincter mechanism and rectal sensation in patients with incontinence or constipation. It can help diagnose Hirschsprung disease and provide biofeedback training for fecal incontinence. A barostat balloon is also inflated during the test to evaluate rectal sensation and accommodation.

Antroduodenal manometry is a manometric method used for evaluation of stomach and duodenal motility. This test is a valuable diagnostic tool for gastrointestinal (GI) motility disorders especially small intestinal pseudo-obstruction which is difficult to make definite diagnosis by clinical manifestations or radiologic findings. Antroduodenal manometry results have been reported to make a change in diagnosis in 8-15% of patients with unexplained nausea, vomiting, and abdominal pain at tertiary care center. Manometric findings that have no evidence of mechanical obstruction and suggestive of pseudo-obstruction with neuropathy or myopathy can avoid unnecessary surgery which resulted in a substantial positive impact on patient management.

Indication for Antroduodenal Manometry

Patients who have small bowel dysmotility may present with non-specific symptoms such as abdominal pain, bloating, nausea, vomiting, constipation or diarrhea. Investigations for small bowel dysmotility should be employed in patients who have these symptoms chronically or intermittently and have at least moderate severity of the symptoms which significantly affect their quality of life. Small bowel motility tests should play role in patients with clinically suspected intestinal obstruction but without obstructive cause, symptoms onset since childhood or adolescence, positive family history of intestinal pseudo-obstruction, or having autonomic neuropathy or other underlying diseases which commonly are associated with GI dysmotility such as systemic sclerosis and amyloidosis.

Technique of Functional and Motility Test: How to Perform Antroduodenal Manometry

Antroduodenal manometry is a manometric method used for evaluation of stomach and duodenal motility. This test is a valuable diagnostic tool for gastrointestinal (GI) motility disorders especially small intestinal pseudo-obstruction which is difficult to make definite diagnosis by clinical manifestations or radiologic findings. Antroduodenal manometry results have been reported to make a change in diagnosis in 8-15% of patients with unexplained nausea, vomiting, and abdominal pain at tertiary care center. Manometric findings that have no evidence of mechanical obstruction and suggestive of pseudo-obstruction with neuropathy or myopathy can avoid unnecessary surgery which resulted in a substantial positive impact on patient management.

Indication for Antroduodenal Manometry

Patients who have small bowel dysmotility may present with non-specific symptoms such as abdominal pain, bloating, nausea, vomiting, constipation or diarrhea. Investigations for small bowel dysmotility should be employed in patients who have these symptoms chronically or intermittently and have at least moderate severity of the symptoms which significantly affect their quality of life. Small bowel motility tests should play role in patients with clinically suspected intestinal obstruction but without obstructive cause, symptoms onset since childhood or adolescence, positive family history of intestinal pseudo-obstruction, or having autonomic neuropathy or other underlying diseases which commonly are associated with GI dysmotility such as systemic sclerosis and amyloidosis.

In general, antroduodenal manometry provides benefit among the following groups of patients,

1.     Suspected small intestinal pseudo-obstruction

2.     Unexplained abdominal pain and nausea/vomiting

3.     A part of GI motility tests to exclude diffuse GI motility disorder

Studies demonstrated that patients who had small intestinal pseudo-obstruction had the abnormal motility patterns which were not presented in healthy individuals and were different from mechanical obstruction. Moreover, among patients who had clinically suspected small intestinal pseudo-obstruction but with normal manometric findings, the diagnosis was finally turned out to be psychiatric or other organic diseases such as Munchausen syndrome-by-proxy, celiac disease and multiple food intolerance. The manometric abnormalities in intestinal pseudo-obstruction and mechanical obstruction will be described later. Antroduodenal manometry should not be performed in patients with symptoms and signs suggestive of small intestinal obstruction unless mechanical obstruction has been excluded by radiologic or endoscopic methods. In addition, fluid resuscitation, bowel decompression, as well as electrolyte imbalance correction should be done prior to the study if clinically indicated. Antroduodenal manometry should be a part of motility test to exclude diffuse GI dysmotility before colectomy in colonic inertia patients. The small intestinal dysmotility was reported in 60% of these patients and the normal antroduodenal manometry result was associated with better long-term post-operative outcome.

Technique and Devices

Baseline measurements of stomach and small intestinal motility at fasting period as well as the effect of meal on stomach and small intestinal activity at post-prandial period have to be evaluated. Therefore, the patients should fast for at least 8 hours prior to the study and medications that affect GI tract motility have to be withheld for at least 3-7 days.

Devices

To measure the intraluminal pressure, the instrument requires lumen obliterating contraction to activate pressure transducer on the catheter. Typically, 2 types of catheter have been used for antroduodenal manometry with different advantages and limitations: (1) water perfused and (2) solid state catheter.

Water perfused catheter system

This catheter has multiple recording side holes with any desirable interval space which usually is 5-10 cm at duodenal part and 0.5-1 cm at antral and pyloric part. Each recording channel is connected with low compliance pneumohydraulic perfusion system with typically perfused rate of 0.1-0.3 mL/minute. Patients using this system especially who have prolonged recording time may receive large amounts of water from system perfusion and may feel uncomfortable or be stressful due to immobilization. Monitoring of pyloric pressure activities is difficult because of the migration of the recording site in relation to the pyloric sphincter. The catheter with additional transpyloric sleeve (Dent sleeve) that incorporates several closely spaced (3-5 mm) pressure transducers can be positioned across the pylorus and used for sphincter pressure measurement to minimize the effect of catheter movement. The advantages of water perfused catheter are that it is relatively inexpensive and widely available.

Solid state catheter

This type of catheter has the microtransducer sensors which are vary in the sensor number and the spacing of each sensor that is placed along distal end of a catheter. The solid state catheter system is highly portable and more comfortable for patients. The system with portable data logger can be used for 24-hour ambulatory antroduodenal manometry monitoring.

Recently, the high-resolution manometry (HRM) system was introduced. This catheter incorporates up to 36 circumferential pressure sensors spaced at 1-2 cm intervals and the data can be displayed as traditional pressure tracings or contour plots which are easily recognized. When comparing the conventional water perfused or solid state system, this high-resolution system is able to demonstrate more details on small bowel pressure profile as well as the pyloric pressure at different contraction phase. Several pyloric activity abnormalities including atonic pattern or sustained elevation of the pyloric baseline pressure which independently occurred or superimposed on phasic activity, prolonged duration of total pyloric activity during fasting and post-prandial period, as well as a prolonged (≥ 3 minutes) and intense (≥ 10 mmHg) tonic contraction or pylorospasm have been described in diabetic gastroparesis patients more than control subjects. Pyloric injection of botulinum toxin A has been reported to improve patients with gastroparesis in several uncontrolled studies. However, more evidence is needed to determine whether patients with gastroparesis secondary to pyloric spasm diagnosed by the HRM study will receive benefit from the botulinum toxin treatment.

The potential limitation of the HRM technology is that it is very sensitive and frequent movement artifacts as well as physiological artifacts such as respiratory activity and pulsations from nearby major vessels may be confusing. In addition, the solid state and HRM system are more expensive than water perfused system.

Catheter Placement

Antroduodenal manometry catheter is usually inserted through the nose under fluoroscopy guidance without using endoscope to avoid duodenal air over-inflation may inhibit antral contraction. However, in some difficult cases such as gastroparesis, catheter placement can be facilitated by using guidewire with endoscopic guidance. Effect of sedatives on intestinal contraction have been reported. Midazolam increased the duration and contraction amplitudes of phase III migratory motor complex (MMC) in the proximal duodenum and shortened the duration of the migrating motor complex. The catheter should be placed until it lay just beyond the ligament of Treitz or about 20 cm length in small intestine to adequately evaluate the antral and duodenal activities. Typically, if using the catheter with 8 site holes, 3 distal recording sites are placed within the duodenum and 5 proximal side holes which have narrower space interval are placed within antrum and pylorus. The catheter location should be checked periodically by fluoroscopy or by normal wave frequency pattern recognition throughout the study and prior to catheter removal at the end of the study.

Study Duration

Normally, the total recording time for stationary manometry is at least 6 hours; 4 hours for fasting period followed by standard meal ingestion and next 2 hours for studying post-prandial period. However, the longer ambulatory monitoring is possible when using solid state catheter with mobile recording assemblies. This system allows 24 hours or more recording time in which more stomach and intestinal contraction patterns during different activities and diurnal motility changes can be revealed. Moreover, the long recording time with multiple meal responses and monitoring at home environment may reduce the intra-individual and inter-individual variability. Studies comparing between ambulatory recording and stationary recording revealed a higher accuracy of ambulatory recording for evaluation of inter-digestive abnormalities and also allows assessment of the relationship between symptoms that may be intermittent with motor abnormalities. The retrograde migration of catheter especially after meal ingestion can lead to incomplete evaluation of abnormal fed response of antrum which may be associated with a number of dysmotility disorders. This problem may limit the usefulness of ambulatory recording in which the location of catheter cannot be periodically checked.

Provocative Tests

Provocative test using medications that specifically stimulate stomach and/or small intestine can be performed to demonstrate abnormal responses in these regions. Typically, erythromycin 3 mg/kg/hr infusion and octreotide 100 µg subcutaneously have been used for study during fasting state. A study in healthy subjects showed that erythromycin induced phasic antral contractions which mimicked MMC within 15 minutes. These antral phase III contractions had significantly more prolonged duration but similar frequency and propagated into small intestine as the naturally occurring phase. The erythromycin-induced phase III contraction in the proximal duodenum showed no difference in duration and frequency from spontaneously occurring phase. In contrast, the duration of phase III in the proximal jejunum was shorter and had slower migration after erythromycin infusion thaaturally occurring phase III. This drug may be used during motility testing to induce antral phase III activity if it fails to occur spontaneously. Erythromycin administered at high dose (12 mg/kg/hr) produces a different effect on gastric motility.^{http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3714419/ – B31} It does not induce antral phase III activity after infusion but induces high amplitude antral pressure wave during the first hour.^{http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3714419/ – B31} In contrast, octreotide initiates small intestinal phase III activity but suppresses antral phase III activity during fasting and post-prandial period in healthy subjects within 30 minutes after injection. These increased intestinal phase III activities have longer duration and greater propagation velocity than spontaneous migratory complexes and are associated with decreased phase II duration. It has been reported that octreotide can restore stomach and small intestinal motility in scleroderma patients with intestinal pseudo-obstruction to the contraction profiles which are similar to those of healthy controls. The provocative tests may provide benefit for evaluation of therapeutic response of these agents which may be associated with long-term positive effect .

Figure 1. “Fed-response” – a termination of migratory motor complex then irregular and frequent contractions occurred immediately after meal ingestion.

Figure 2. After octreotide injection, phase III antral contractions (at most upper channel) were inhibited but duodenal contractions (lower channels) were stimulated (phase III MMC like activity with rapid propagation).

Neuropathic Pattern

In the intrinsic (enteric) neuropathic process, normal amplitude contractions are preserved but the un-coordinated or disorganized configuration or propagation of MMC or phase III MMC is demonstrated. In contrast, in the extrinsic (autonomic) neuropathy, an impaired fed response and postprandial antral hypomotility are observed.

Figure 3 A case of intestinal pseudo-obstruction – burst of phase II contractions and disorganized phase III migratory motor complex (both antegrade and retrograde phase III MMC) were demonstrated.