RADIOLOGICAL EXAMINATION OF THE URINARY TRACT

RADIOLOGICAL EXAMINATION OF THE URINARY TRACT

THE URINARY TRACT INVESTIGATION

The following radiological and imaging methods are available for the investigation of the urinary tract:

1.      Simple radiology

2.      Intravenous urography

3.      Retrograde pyelography

4.      Antegrade pyelography

5.      Renal angiography

6.      Cystography, cystourethrography and dynamic bladder studies

7.      Urethrography

8.      Cyst puncture

9.      Ultrasound

10.   Computed tomography

11.   Isotope imaging and renography

12.   MRI.

Plain X-rays

Plain X-rays of the renal tract are taken as a routine before most kidney investigations. Good quality films will often show the renal outlines quite clearly, and gross enlargement of the kidney by hydronephrosis or tumour may be readily recognised. Similarly, gross shrinkage of the kidney from chronic pyelonephritis or from renal ischaemia may be diagnosed.

Calcification in the renal areas is most commonly due to renal calculi in the calyces or renal pelvis. Nephrocalcinosis, or calcification within the renal substance, is much less common, and is seen in such rare conditions as hyperparathyroidism, renal tubular acidosis, and medullary sponge kidney. Calcification may also be observed in the kidney in renal tuberculosis, and occasionally in renal tumours.

Plain X-rays will also demonstrate opaque calculi in the ureter and in the bladder. Calcification in the bladder wall and ureter is seen in schistosomiasis. Very rarely calcification may be detected in bladder tumours due to encrustations on the surface of a tumour.

Fig.  Laminated bladder calculus shown by plain X-ray.

Intravenous urography (IVU)

Provided that the kidney is functioning and the blood urea is not too high, intravenous urography will demonstrate most lesions affecting the normal anatomy of the renal drainage system.

Congenital anomalies, such as double pelves and ureters, or duplex and horse-shoe kidneys, can be diagnosed with certainty. Polycystic kidneys can also be identified unless renal failure has supervened. In a typical case both kidneys are enlarged, and there are multiple calyceal deformities.

Local distortion of the renal calyces by a kidney mass is often seen on urography. In many of these cases it is impossible to differentiate between hypernephroma and a simple cyst from the pyelogram. In such cases imaging by ultrasound will provide a definitive answer and is the next investigation of choice. CT will also differentiate renal tumour from cyst. If a cyst is demonstrated the diagnosis can be confirmed by percutaneous cyst puncture, and the cyst can then be emptied by aspiration. If a tumour is diagnosed or suggested by ultrasound the diagnosis can be confirmed by CT. This will also help staging and show whether the renal vein is involved. Arteriography will also confirm the diagnosis of tumour, but is now little used except where embolisation is being considered.

 

Fig. Polycystic kidneys. Note the bilateral splaying and deformity of the minor calyces and large size of the kidneys.

Opaque or suspected non-opaque renal calculi may be further investigated by intravenous urography. The relationship of an opaque renal calculus or of a suspected renal calculus to the ureter, pelvis or calyces is clearly demonstrated. Non-opaque calculi are shown as filling defects which may be obstructing the renal drainage system and causing hydroureter and hydronephrosis proximal to the level of the obstruction.

 

Fig. Hydronephrosis with a calculus in the dilated lower calyx.

The bladder is also well shown at intravenous urography. Bladder tumours whether papillomatous or carcinomatous can be demonstrated though such tumours may be better visualised by cystography. With carcinoma, assessment by ultrasound, CT or MRI may be required for staging.

Fig. MRI study of bladder carcinoma (arrow), b = bladder; r = rectum;= nodal metastases on left side of pelvis.

 

Prostatic lesions with bladder-neck obstruction are often assessed by intravenous urography. The enlarged prostate may show as a large rounded filling defect at the neck of the bladder. The bladder itself may show trabeculation and thickening of its wall and there may also be evidence of back pressure on the kidneys. Diverticula of the bladder, which are more frequent in the elderly patient with bladder-neck obstruction, can also be seen. In prostatic problems it is important to obtain a film or ultrasound scan of the bladder after micturition, as the amount of residual urine gives a good index of the degree of obstruction.

Hypertension of possible renal origin is investigated by intravenous urography in the first instance. This will demonstrate unilateral or bilateral hydronephrosis and will direct attention to the unilateral nonfunctioning kidney or to polycystic kidneys. Intravenous urography may also show a characteristic pattern in hypertensive patients in whom the cause is unilateral ischaemia of a kidney. In these patients, in whom the usual causative lesion is an atheromatous plaque stenosing the main renal artery the ischaemic kidney is small and shows increased density of contrast in the pelvis and calyces as the examination proceeds. This is because there is a greater percentage of water resorption on the affected side than on the normal side.

Fig. Atheromatous renal artery stenosis shown by renal arteriography.

Retrograde pyelography

Retrograde pyelography is performed after cystoscopy and the insertion of a radiopaque ureteric catheter by the surgeon. A small quantity of sterile contrast medium is injected up the catheter to outline the renal tract and appropriate films are taken. The retrograde pyelogram was once used as a method of clearly defining the anatomy of the renal drainage system in the patient with a non-functioning kidney or with a poorly functioning kidney when intravenous pyelography had failed to provide adequate visualisation. It is less widely practised today than in the past because the modern intra­venous contrast media with the use of high dosage and delayed films often provide diagnostic results where the older contrast media might have been unsuccessful, and also because cases of suspected tumour or cyst are now usually investigated by ultrasound or other methods mentioned above.

Retrograde pyelography is still sometimes used to confirm or disprove the relationship of a suspected small calculus to the ureter. It is also sometimes used to help dislodge a ureteric calculus and ‘oil’ it down the ureter.

Antegrade pyelography (percutaneous nephrostomy)

Percutaneous antegrade pyelography is a useful method of demonstrating the renal calyces, pelvis and ureter in cases of suspected urinary tract obstruction where the intravenous method has been unsuccessful or inconclusive. Unlike retrograde urography it does not require GA and it has a lower incidence of urinary tract infection. It is also useful in infants and children where cystoscopy is difficult or impossible.

A dilated renal calyx is punctured percutaneously from the lumbar region using a fine needle, and contrast medium is injected. The technique can also be used to insert a catheter and provide temporary drainage. The catheter tract can also be used for a percutaneous approach to renal calculi and for stent insertions.

Renal angiography

An opaque catheter is passed percutaneously into the aorta and its preshaped tip is screened into the renal artery origin with the aid of an image intensifier. The whole renal circulation can be beautifully demonstrated using only a small quantity of low-concentration contrast medium.

The renal angiogram in the past provided a method of making a preoperative differential diagnosis in the difficult cases in which a mass had been demonstrated in the kidney but it was uncertain whether this was due to a tumour or cyst. The typical hypernephroma shows excessive vascularity with pathological vessels throughout the tumour area. The typical cyst appears as a large rounded defect in the angiogram. The method was highly accurate in differentiating between tumours and cysts though occasionally a non-vascular tumour was encountered which gave rise to difficulty. As noted above ultrasound or CT now provide simpler methods of confirming the diagnosis of renal cyst or tumour.

Renal angiography has also been widely used for the embolisation of vascular tumours and for the investigation of renal hypertension. A small proportion of patients with hypertension are suffering from renal ischaemia with secondary hypertension. The usual cause is an atheromatous narrowing of the origin of a renal artery. Other less common causes of renal artery stenosis include a peculiar condition occurring mainly in female patients and termed fibromuscular hyperplasia of the renal artery (Fig. 10.9). Renal artery stenosis shown by angiography caow be treated by percutaneous dilatation with a Gruntzig balloon catheter.

Fig. Atheromatous renal artery stenosis shown by renal arteriography.

Fig. Fibromuscular hyperplasia (1) shown by renal angiography.

Cystography

Cystography is performed after passage of a catheter into the bladder and injection of contrast medium. The method is useful for outlining tumours of the bladder when intravenous urography has been unsuccessful or equivocal. Ultrasound can also be used to demonstrate bladder tumours and CT or MRI enables such tumours to be assessed and staged.

Attention has been drawn to the frequent occurrence of vesicoureteric reflux and to the importance of this condition in the pathogenesis of chronic pyelonephritis. It is claimed that vesicoureteric reflux is present in a high proportion of patients with chronic pyelonephritis, and that it may be an important aetiological factor. Reflux is best demonstrated by performing a micturating cystogram, though it may occur spontaneously when the bladder is well filled. As the patient micturates, reflux up the ureters may be seen as the bladder contracts.

Fig. Spontaneous vesicoureteric reflux after injection of the bladder through an indwelling catheter. There is already gross hydroureter and hydronephrosis. (Urethral obstruction in a child due to congenital valves.)

Cystourethrography

This examination is used for the investigation of bladder-neck obstruction in males, the various forms of bladder-neck disturbance seen in postpartum females, and other disorders of the peripheral control of micturition. The technique is to fill the bladder via a catheter which is then removed. The act of micturition is observed on the screen and films of the bladder-neck and urethra taken during micturition. As already noted, vesicoureteric reflux may be observed during this procedure and is an important finding. The procedure is performed with the aid of an image intensifier. This has the added advantage that it is possible to take a video film or videorecord of the act of micturition. This can then be played back and details observed at leisure.

Dynamic bladder studies are indicated in more complicated bladder problems with incontinence, frequency, disorders of storage function and voiding, neuropathic bladder and postoperative disturbed function. Various physiological measurements are superimposed upon a video image of the bladder and urethra during filling and voiding. These measurements are the abdominal and bladder pressures (recorded by rectal and bladder transducers respectively), the detrusor or intrinsic bladder pressure (the recorded bladder pressure minus the abdominal pressure) and the urine flow rate. Analysis of these synchronous recordings permits improved evaluation of the mechanisms of the bladder dysfunction.

Urethrography

Urethrography in the male is usually performed by injection of a viscous contrast medium which provides excellent contrast through­out the urethra. The contrast medium is injected after insertion of a tight-fitting nozzle into the meatus and the whole of the urethra is outlined. Obstruction by a stricture can then be localised, and in the case of prostatic problems the prostatic urethra can be carefully studied.

Cyst puncture

Renal cysts can be punctured percutaneously from the lumbar region. This is best done under ultrasound control when the point of puncture and the depth and size of the cyst can be assessed. The straw-coloured fluid they contain is aspirated. Once the cyst is entered it can be outlined by injecting a small quantity of contrast medium. This will show the size of the cyst and the contrast can be used to confirm that most or all of the fluid has been aspirated.

Ultrasound

The kidneys are well shown by ultrasound which has the valuable property of distinguishing between renal solid masses and renal cysts. Cysts can also be localised by ultrasound for percutaneous puncture. Hydronephrosis is also well demonstrated by ultrasound as are polycystic kidneys. In the field of renal trans­plantation ultrasound is valuable in showing perirenal fluid and lymph collections (lymphoceles) and confirming swelling of the kidneys associated with rejection.

The distended bladder is also well shown by abdominal ultrasound and tumours including infiltration of the wall can be assessed. The prostate can also be demonstrated, but is best examined by endoscopic transrectal ultrasound. This is now widely used for ultrasound-guided biopsy of suspected prostatic carcinoma and other prostatic lesions.

Most early carcinomas show as low density areas in the subcapsular zone but require biopsy for confirmation since the appearance is non-specific. Patients with a raised prostatic serum antigen (PSA) level or clinical suspicion of prostatic carcinoma may require multiple biopsy of the prostate under ultrasound guidance.

 

Fig. Longitudinal ultrasound scan of normal kidney. The renal sinus is echogenic. The pyramids are relatively hypoechoic compared with the remainder of the parenchyma. The dense echoes (arrows) at the bases of the pyramids are due to the arcuate arteries.

Fig. Parasagittal section. Simple renal cyst.

ISOTOPE SCANNING

“Tc^m DMSA (dimercaptosuccinic acid) is widely used for renal imaging. This compound is fixed in the tubules with a low extraction rate and good images may be obtained 1-2 hours after injection.

Lesions such as tumours show as filling defects as do benign lesions such as cysts (Fig. 10.14). In chronic pyelonephritis uptake is often reduced and uneven as it is in other conditions with poor renal function, such as obstructive uropathy and tuberculosis.

Renography. This method of scanning is widely used in renal’ disease. It differs from normal scanning in that a graph is obtained of the renal output of the isotope. The radioisotope used is usually ¹³¹I-hippuran or ¹²³I-hippuran. This is removed almost entirely from the kidney in one passage and is not reabsorbed. Scanning must therefore take place immediately after a small intravenous injection of the radioactive isotope. A scintillator counter is centred evenly over each kidney touching the skin. The normal renogram graph usually shows:

1.    A sharp rise of activity within 30 seconds of the injection (A-B)

2.    A slower rise during the next 3 to 5 minutes (B-C)

3.    Falling off in the next 15 minutes (C-D).

This is the normal pattern but it will be changed in various ways depending on the type of disease from which the kidney is suffering.

Comparison of the function of the two kidneys is also possible by comparing the results on the two sides.

 

 

 

Fig. Right renal cyst. ⁹⁹Tc^m DMSA scan. Posterior projection. (A) Normal left image. (B) There is a non-specific deficit in the upper half of the right kidney due to a cyst.

Fig.  ¹³¹I-hippuran renogram. Normal. For explanation see tex

CT

Tumours, cysts and various other lesions of the kidneys are all well shown.  CT is particularly valuable in the patient with a non functioning kidney in demonstrating the cause. It may even prove whether a kidney is present or not when this remains doubtful by other techniques. It will readily differentiate between renal tumours and cysts and is invaluable for the staging of renal tumours.-

Fig. CT scan showing a large simple cyst on the left side and a small simple cyst on the right side

Fig. Ultrasound scan shows large rounded tumour (arrows) above upper pole of right kidney

MRI

Magnetic resonance imaging is now widely used in the assessment and staging of both bladder and prostatic tumours. It appears superior to CT in both these areas by virtue of its greater tissue differentiation ability and its easy multiplanar potential.

PLAIN   FILMS

A plain abdominal film is essential prior to urinary tract investigation. This may show: renal calculi in the pelvicalyceal system, renal parenchymal calcification, ureteric calculi, bladder calcification and calculi, prostatic calcifi­cation or sclerotic bone deposits.

Caution should be used in interpreting renal-tract calcification as overlying calcified mesenteric glands and pelvic vein phleboliths are often mistaken for ureteric calculi. Inspiration and expiration films change the position of the kidneys and often confirm that a calcified area in the upper abdomen is a calculus.

INTRAVENOUS  UROGRAPHY  (IVU)

The indications for this examination are haematuria, renal calculi, ureteric colic or suspected calculi. Patients with urinary retention and urinary tract-infection should initially have an ultrasound rather than an IVU. Patient preparation:

•  A laxative the day before the examination to clear gas and faecal shad­owing from the abdomen so that the renal outlines are not obscured.

•  Fluid restriction for 6-8 hours prior to the examination to increase concentration of the urine and produce a denser pyelogram. Patients in renal failure, and those with diabetes and multiple myeloma should not be dehydrated.

•  Elicit a history of iodine allergy prior to intravenous injection and do not proceed if positive.

After a preliminary control film of the abdomen, 50-100 ml of a low osmolar iodinated contrast medium is injected. Contrast rapidly reaches the kidney and is excreted by glomerular filtration. A film taken shortly after injection demonstrates the nephrogram phase showing the renal parenchyma and outline. Films after 5, 10 and 15 minutes reveal contrast in the pelvicalyceal systems, ureters and bladder; the series is varied accord­ing to the individual patient. Renal obstruction may require a delayed study up to 24 hours to outline the pelvicalyceal system.

RETROGRADE   PYELOGRAPHY

A retrograde pyelogram is occasionally necessary when detail of the pelvi-calyceal system and ureter is not adequately delineated by intravenous contrast, especially when there is suspicion of an epithelial tumour of the urinary tract. In theatre, a catheter is placed into the ureter after a cys­toscopy; contrast injected through the catheter outlines the pelvicalyceal system and ureter.

MICTURATING  CYSTOGRAM

A catheter is inserted in the bladder which is filled to capacity with con­trast. After catheter removal, films are taken of the renal tract as the patient is micturating, looking for vesico-ureteric reflux. Careful examina­tion of the urethra in the oblique position is necessary in suspected ure­thral valves, as they are usually only demonstrated during micturition.

ANTEGRADE   PYELOGRAPHY

If for technical reasons, a retrograde pyelogram is not possible (e.g. after cystectomy), a fine-gauge needle, under local anaesthetic, can be inserted directly into the pelvicalyceal system and contrast injected to visualize the calyces, pelvis and ureter. The patient lies in a prone position and the examination is carried out under either ultrasound or fluoroscopic control. This procedure, not requiring a general anaesthetic, accurately localizes the site of an obstructing lesion, such as a calculus or stricture.

Fig. Antegrade pyelogram showing ureteric obstruction by a non-opaque

calculus (arrow).

PERCUTANEOUS NEPHROSTOMY

Provides temporary drainage of an obstructed kidney by percutaneous insertion of a catheter directly into the pelvicalyceal system.

URETHROGRAPHY

The adult male urethra can be visualised by:

•  Ascending urethrography: contrast is injected into the meatus and films obtained of the urethra.

•  Descending urethrography: after filling the bladder with contrast, the catheter is removed and films of the urethra are taken during micturition.

In both studies, the entire urethra must be studied.

ULTRASOUND

Ultrasound is one of the most valuable investigations of the urinary tract and the investigation of choice in children. It is extremely effective in evaluating renal size, growth, masses, renal obstruction, bladder residual volumes and prostatic size; it is non-invasive and can be repeated fre­quently. Ultrasound probe technology has shown great recent advances and exact details can be obtained by the technique of endo-ultrasound — imaging after insertion of the probe in the rectum or vagina.

Fig. Normal renal ultrasound.

COMPUTED  TOMOGRAPHY  (CT)

This aids assessment of renal masses, obstruction, retroperitoneal disease, staging of renal and bladder neoplasms, tumour invasion into the renal vein or inferior vena cava (IVC), and evaluation after trauma, surgery or chemotherapy.

ISOTOPES

•  Static scanning: technetium-99m DMSA: selective uptake by the renal cells with stagnation in the proximal tubules produces images of the renal parenchyma.The isotope is used to assess function, position, size and scar­ring of kidneys.

•  Dynamic scanning: technetium-99m DTPA: isotope clearance by glomerular filtration produces a dynamic scan, providing information on renal blood flow and renal function. The function of each individual kidney can be assessed as well as total renal function.

Fig. DMSA scan showing relative function of each kidney.

ARTERIOGRAPHY

Evaluation of the renal arterial circulation may be necessary for:

•  further investigation of equivocal renal masses: renal cell carcinomas are usually hypervascular with a pathological circulation;

•  arteriovenous malformation;

•  renal artery stenosis;

•  anatomical details prior to renal transplantation, or suspected vascular occlusion after surgery.

Fig.  Horseshoe kidney: fusion of the lower poles with medially pointing calyces.

Fig.  Crossed renal ectopia

CONGENITAL RENAL ANOMALIES

Unilateral renal agenesis. During urinary-tract investigations an incidental absence of a kidney may be discovered. Technetium-99m DMSA isotope scan will confirm this finding.

Renal hypoplasia. The kidney is small but perfectly formed.

Horseshoe kidney. Fusion of the opposite renal poles (usually the lower). There is an increased incidence of: pelvi-ureteric junction (PUJ) obstruc­tion; renal calculi; infection.

Crossed fused renal ectopia. One kidney is displaced across the midline and fused to the other normal kidney; ureteric orifices lie in a normal position.

Pelvic kidney. May be associated with vesico-ureteric reflux and hydronephrosis due to an abnormal ureteric insertion.

Duplex kidney. The commonest renal anomaly with a variable degree of duplication ranging from minor changes of the renal pelvis, to total dupli­cation of the renal pelvis and ureter.

Fig. Left duplex kidney; the ureters join in the pelvis

                                  

Fig. Pelvic kidney (arrow).

POLYCYSTIC KIDNEYS

Polycystic kidneys are characterized by enlargement of both kidneys with replacement of normal renal tissue by multiple cysts. Expansion and enlargement of cysts compress the renal substance, leading to loss of function and eventually renal failure.

Polycystic disease of adults:     Inherited as an autosomal dominant with

nearly 100% penetration.
Polycystic disease of                Presents at 3-5 years of age with enlarged

childhood:                               kidneys and hepatic fibrosis.  Death may

               result from portal hypertension.
Polycystic disease of the          Discovered in the first few days of life

new-born:                                 with renal failure and gross enlargement of bothkidneys.

PRESENTATION

Manifestations of adult polycystic disease usually arise in the third and fourth decades: haematuria; palpable abdominal mass; proteinuria; renal failure.

RADIOLOGICAL  FEATURES

Renal enlargement is often of massive proportions.

•   Intravenous urography may show elongation, deformity and distortion of the calyces. The renal pelvis may also be deformed by cysts protruding into it.

•   Ultrasound and CT accurately measure the renal size and assess the number and distribution of cysts.The disease may be diagnosed antenatally by ultrasound.

•   Technetium 99m scanning will assess renal function.

ASSOCIATED   FEATURES/COMPLICATIONS

•   Cysts in the liver, pancreas and spleen.

•   Increased incidence of intracranial aneurysms. Rarely, polycystic disease may first manifest itself by signs and symptoms of a ruptured intracranial aneurysm (subarachnoid haemorrhage).

•   Hypertension.

•   Renal calculi.

•   Urinary-tract infections.

•   Uraemia: may eventually need dialysis or renal transplantation.

Fig. Polycystic kidneys: IVU demonstrating enlarged kidneys with a distorted calyceal pattern.

Fig. CT abdomen: multiple cysts in the kidneys and liver.

RENAL CYST

Simple renal cysts are extremely common, occurring with increasing fre­quency as age progresses. They are often multiple, of varying size and usually an incidental finding. Renal cysts are almost always asymptomatic, of little clinical significance, and usually require no further treatment.

RADIOLOGICAL  FEATURES

•  Intravenous pyelography: cysts appear as mass lesions causing a bulge in the renal outline, often with pelvicalyceal distortion.

•  Ultrasound: well defined with few or no internal echoes and transmission of the sound beam with posterior acoustic enhancement.

•  CT: sharply delineated homogeneous lesions with no enhancement after intravenous contrast.

•  MRI: well circumscribed low signal lesion (black) or a uniform high signal (white) depending on the type of sequence used (TI orT2).

Complicated cysts (haemorrhagic cysts, calcified cysts, cysts with inter­nal septations) need follow up with possible needle aspiration for cytology or histology.

 

Fig. Ultrasound: simple renal cyst

Fig.  CT showing a well-defined right renal cyst.

 

RENAL PELVIC/URETERIC TUMOURS

Tumours arising from the urinary tract epithelium are usually transitional cell carcinomas. They may be polypoidal, plaque-like or form strictures. Squamous cell carcinoma is often associated with either calculi or chronic infection such as schistosomiasis. Haematuria is the main presenting symptom.

RADIOLOGICAL  FEATURES

The majority of urothelial tumours produce an intraluminal mass seen on intravenous urography as irregular filling defects, occasionally villous or lobulated. Ureteric tumours often exhibit a localized dilatation of the ureter at the site of the tumour, but sometimes antegrade or retrograde pyelography is necessary for further evaluation. Ureteroscopy with biopsy will confirm the findings.

Differential diagnosis of filling defect in ureter/renal pelvis

•  Calculus.

•  Blood clot.

•  Tumour.

•  Papillary necrosis (diabetes, analgesic abuse).

Fig. Filling defect in the right renal pelvis (arrow), proved to be a transitional cell carcinoma

RENAL-TRACT OBSTRUCTION

Obstruction to the renal tract may occur at many sites: the pelvicalyceal system, ureter, bladder or bladder outlet. The commonest cause is a ureteric calculus but tumours of the urinary tract or extrinsic ureteric invasion from rectosigmoid or gynaecological tumours are also well-recognized causes. If left untreated, renal atrophic changes may follow.

RADIOLOGICAL  FEATURES

The different imaging modalities all diagnose renal tract dilatation.

•   Ultrasound. This is the initial investigation of choice. The distended collecting system is seen as an echo-free area in the centre of the kidney.

•   IVU. Excretion of contrast is delayed with distended and clubbed calyces, often with ureteric dilatation down to the level of obstruction. Slow excretion of contrast may require delayed films up to 24 hours.

•   CT. Demonstrates the distended collecting system and ureters as well as detecting extrinsic causes of obstruction, such as tumours.

•   Isotope scanning. Identifies a slow accumulation and clearance of isotope in the collecting system

Fig. Causes of renal-tract obstruction.

Fig. IVU showing bilateral dilated calyces and ureters in bladder outlet obstruction

Fig. CT scan: unrelieved obstruction leading to renal atrophy of the left kidney.

 

Fig. Ultrasound: renal obstruction showing dilated calyces.

RENAL ARTERY STENOSIS

Renal artery stenosis results from a narrowing of the renal artery leading to reduction in perfusion pressure, hypertension and a decrease in renal size. It is usually atherosclerotic iature and may be uni- or bilateral.

PRESENTATION      

•   Hypertension.

•   Deteriorating renal function.

RADIOLOGICAL  FEATURES

•   Ultrasound may demonstrate a small kidney. A Doppler examination may show abnormal flow patterns in the renal artery with an increased peak systolic velocity.

•   Intravenous urography is not reliable and may be entirely normal but clas­sically the affected side shows:

delayed appearance and a slow excretion of contrast medium; reduction in pole to pole diameter of 3^s 1.5 cm;

increased concentration of contrast medium in the pelvicalyceal system, because of greater salt and water reabsorption from a slower tubular passage.

•   Isotope scanning does not accurately diagnose stenosis but may demon­strate a reduced uptake in the affected kidney, with a delay in peak concen­tration.

•   Renal arteriography is the definitive investigation to show the narrowing, with selective catheterization, and contrast injection into the renal arteries. Stenoses may be due to:

•   Atheroma: commonest cause with stenosis of the proximal artery.

•   Fibromuscular hyperplasia: a condition of unknown aetiology, most commonly seen in young women. Irregular intimal hyperplasia gives rise to a beaded appearance with stenosis in the distal renal arteries.

TREATMENT

o       Balloon angioplasty or insertion of metallic stents.

o       Surgical reconstruction of the renal artery:
vein patch graft;

o       splenic artery revascularization; prosthetic by-pass graft.

Fig. Selective left renal arteriogram: stenosis at the origin of the left renal artery (arrow).

Fig. Renal artery angioplasty with balloon inflation in the stenosis

 

 

 

RENAL CARCINOMA

Renal carcinoma arises from the renal tubular epithelium, an adenocarci­noma (hypernephroma) and up to 10% may be bilateral.

Wilms’tumour (nephroblastoma) is one of the more common malignancies occurring in children and these may also be bilateral in up to 10%.

Transitional cell carcinomas arise from the epithelium lining the pelvicalyceal system.

Secondary malignant infiltration of the kidneys may be occasionally encoun­tered in lymphoma or leukaemia.

PRESENTATION

Pyrexia; haematuria; polycythaemia; first symptoms from secondary deposits to lung, bone, liver or brain such as haemoptysis, cough or patho­logical fractures; left varicocele if the left renal vein is occluded by tumour.

RADIOLOGICAL  INVESTIGATION

Numerous investigations are available including: plain films; intravenous urography; ultrasound; CT; MRI; arteriography and isotope bone scan (for secondary deposits).

RADIOLOGICAL  FEATURES

•  Plain films: occasionally show fine stippled or even curvilinear calcifica­tion in the renal mass.

•  Intravenous urography: may reveal a soft-tissue mass causing a bulge in the renal outline, an enlargement of the kidney or pelvicalyceal distortion and irregularity. A large tumour may give rise to a completely non­functioning kidney.

•  Ultrasound: highly accurate in distinguishing between a solid carcinoma and a benign cyst. Blood-flow characteristics of the renal tumour can be ascertained and in doubtful cases a biopsy taken under ultrasound control.

•  CT/MRI: useful for staging to determine: calcification, size and density of the mass; perinephric tissue invasion; invasion into the renal veins and infe­rior vena cava; lymph-node enlargement.

•  Arteriography is not often indicated but when utilized may demonstrate a pathological circulation in the vast majority of carcinomas.

DIFFERENTIAL  DIAGNOSIS  OF   RENAL  MASS

•  Non-malignant: renal cysts, inflammatory masses, haematoma.

•  Benign: adenoma, haemangioma, papilloma, angiomyolipoma.

•  Malignant: renal cell carcinoma, transitional cell carcinoma, Wilms’ tumour (nephroblastoma).

Fig. IVU: mass in the lower pole of the right kidney causing calyceal distortion

Fig. Contrast enhanced CT: large right renal carcinoma. Note simple cyst in the left kidney.

 

Fig. Arteriogram demonstrating a pathological circulation in renal carcinoma.

 

TUBERCULOSIS OF THE URINARY TRACT

After pulmonary tuberculosis, the renal tract is the most common site of infection, usually due to haematogenous spread either from pulmonary or bone tuberculosis. Any part of the renal tract may be involved: kidneys, ureters, bladder, seminal vesicles and epididymis.

RADIOLOGICAL   FEATURES

A chest film should be performed to exclude pulmonary tuberculosis. Plain abdominal films may reveal calcification in the kidneys, seminal vesi­cles or vas deferens. Calcification is of a variable intensity, ranging from a few small flecks to heavy dense areas in advanced cases. Gross renal disor­ganization may lead to a non-functioning kidney (tuberculous autone-phrectomy).Testicular ultrasound is useful to delineate epidydymitis. On IVU, the following features may be found.

•  Kidneys: deformities of calyces, strictures, irregular cavity formation and scarring of renal parenchyma.

•  Ureters: strictures and areas of narrowing in the ureters, the strictures often being multiple. Spread is usually from the kidneys, so renal abnormal­ities are often found.

•  Bladder: tuberculous cystitis: initially there is mucosal oedema but sub­sequently bladder irregularity with contraction. The bladder has a thick­ened wall, is shrunken and of a small capacity.

Fig. Manifestations of renal-tract tuberculosis

Fig. Tuberculosis: plain film showing coarse calcification in the lower pole of the left kidney.

Fig. Contracted bladder in tuberculosis.

 

UNILATERAL NON-FUNCTIONING KIDNEY

When one kidney is not visualized during intravenous pyelography, it may be absent, lying in an abnormal position, or grossly hydronephrotic. Numerous other causes of non-visualization of a kidney should also be considered. Ultrasound may demonstrate the size, position and degree of obstruction of a non-visualized kidney.

Isotope scanning may also be helpful as it will demonstrate the presence of an ectopic kidney.

CAUSES

•  Chronic obstruction: ureteric obstruction from calculus, tumour or extrinsic invasion will lead to deterioration of function and atrophy.

•  Vascular causes: renal artery occlusion either from severe atheroma­tous disease or following trauma; renal vein thrombosis.

•  Tumour: renal carcinoma infiltrating the whole kidney.

•  Chronic infection: chronic pyelonephritis, tuberculosis.

•  Postnephrectomy.

•  Renal agenesis.

•  Ectopic kidney.

Fig.  IVU: non-visualization of the left kidney.

 

UNILATERAL SMALL KIDNEY

The normal kidney measures 9-14 cm in length, the left usually being larger than the right. However, a difference in size of > 1.5 cm is regarded as significant.

CAUSES

•   Chronic pyelonephritis: reduction in renal size, irregularity of outline due to focal areas of scarring and calyceal deformity. Scarring is most common in the upper pole of the kidney over the dilated calyces.

•   Ischaemia: renal artery stenosis leading to decreased perfusion.

•   Postobstructive atrophy: smooth outline, uniform loss of renal sub­stance, with some dilatation of calyces. Severe obstruction, regardless of the cause, lasting longer than a few days may lead to irreversible loss of renal parenchyma and function, hence the importance of diagnosing and relieving renal-tract obstruction.

•   Congenital hypoplasia: a small kidney with a smooth outline and a normal pelvicalyceal system.

•   Renal infarction: here the scar is opposite a normal calyx.

Fig. IVU: small right kidney with calyceal blunting in chronic pyelonephritis.

 

NEPHROCALCINOSIS

‘Nephrocalcinosis’ refers to calcium deposition in the renal parenchyma, either in the cortex or medulla. The calcification is fairly uniform and may be a consequence of:

•  Hypercalcaemia or hypercalcuria: hyperparathyroidism, usually primary; renal tubular acidosis; sarcoidosis; multiple myeloma.

•  Structural renal abnormality:

medullary sponge kidney —congenitally dilated tubules with deposition of calcium; papillary necrosis.

FOCAL  RENAL  PARENCHYMAL   CALCIFICATION

•  Tuberculosis: variable distribution of the renal calcification.

•  Tumours: renal cell carcinoma.

Fig. Nephrocalcinosis: organized diffuse renal parenchymal calcification.

 

RENAL CALCULUS

The majority of renal calculi are either pure oxalate, calcium oxalate, calcium oxalate with phosphate, uric acid or cystine. Predisposing factors:

·        Stasis due to congenital abnormalities (horseshoe kidney), pelvi-ureteric junction obstruction, renal-tract obstruction and ureterocele.

·        Metabolic causes: hyperparathyroidism; hypercalcuria; uric acid stones after cytotoxic therapy, gout, polycythaemia or after cytotoxic therapy; cystine stones in cystinuria.

·        Infection: typically

·        Proteus infection, often resulting in staghorn calculi.

RADIOLOGICAL  FEATURES

A plain abdominal film will generally reveal calculi as they are radio-opaque, except for uric acid stones which are radiolucent.The majority of calculi form in the calyces and may be seen on intravenous urography as a filling defect in the contrast column.

Staghorn calculi develop in the pelvicalyceal system and are usually easily visualized on plain films.

TREATMENT

•  Extracorporeal lithotripsy (EL).

•  Percutaneous removal under radiological control (nephrolithotomy).

•  Surgery for large staghorn calculi or when EL and percutaneous approach has failed.

 

Fig. Opaque renal calculi: the large medially placed opacity is lying in the renal pelvis

URETERIC CALCULUS

A ureteric calculus tends to be small, often 2-3 mm in diameter, and originates from the kidney. Its progress down the ureter may cause severe abdominal pain; it commonly impacts at the vesico-ureteric junction.

RADIOLOGICAL  FEATURES

A plain abdominal film may identify a small area of calcification in line with the ureter. However, an intravenous urogram is required to confirm that this opacity is a ureteric calculus, usually identified as a filling defect in the contrast-filled ureter. If causing obstruction, there may be a delay in excretion of contrast, with a variable degree of pelvicalyceal distension and ureteric dilatation to the level of the calculus. In severe obstruction, a temporary nephrostomy or double J ureteric stent may be needed.

TREATMENT

•  Majority of calculi more 5mm in diameter pass spontaneously.

•  Upper and lower third ureteric calculi: extracorporeal lithotripsy.

•  Middle third: push calculus into renal pelvis and then lithotripsy.

•  Lower third: endoscopic removal with a basket.

•  Large calculi: may need open ureterotomy.

Fig. Ureteric calculus: plain film and after IVU demonstrating obstruction.

 

BLADDER CALCULUS

Calculi may descend from the kidney into the bladder or result from:

•  urine infection, especially Proteus;

•  urine stasis due to bladder outlet obstruction, bladder diverticulum or neuropathic bladder;

•  foreign bodies in the bladder.

RADIOLOGICAL   FEATURES

Calculi may be missed on plain films due to overlying bony structures, gas and faecal shadowing in the rectum, phleboliths or arterial calcification. When the bladder is filled with contrast, either at IVU or cystography, bladder stones may appear as filling defects. Ultrasound can also detect them as echogenic structures casting an acoustic shadow.

TREATMENT

•   Endoscopic removal with lithotrite.

•   Large calculi may need open removal.

•    Extracorporeal lithotripsy not widely used for bladder calculi.

Fig. Large opaque, laminated bladder calculus.

 

BLADDER DIVERTICULUM

 

A mucosal outpouching from the bladder muscle wall results in a bladder diverticulum.They may be:

•  acquired secondary to lower urinary-tract obstruction or bladder instability;

•  associated with a neurogenic bladder;

•  congenital.

In males, the commonest cause of diverticula formation is a consequence of raised intravesical pressure with detrusor hypertrophy or from obstruction secondary to prostatic enlargement. Diverticula may be mul­tiple and of a variable size, with some reaching enormous proportions.

IVU. Seen as outpouchings from the bladder wall.

Micturating cystography. Visualizes diverticula, especially during micturition when they distend; subsequent emptying of the diverticulum into the bladder at the end of micturition leaves a residual volume and may result in double micturition. Stasis leads to an increased incidence of calculus formation, urinary-tract infection and tumour. Residual urine volume in the bladder and diverticulum may be accurately measured by ultrasound.

Fig. Cystogram demonstrating a large left bladder diverticulum with further smaller diverticula on the right. An inflated balloon catheter is present in the bladder.

URETHRAL STRICTURE

Strictures in the urethra are demonstrated by either a retrograde injection of contrast into the meatus (ascending urethrogram) or after instilling contrast into the bladder, obtaining films as the patient is micturating (descending urethrogram). Strictures present with symptoms of a slow urinary stream and outflow obstruction.

CAUSES

•   Post trauma: following previous instrumentation, catheterization or external trauma. The strictures most commonly occur at the penoscrotal junction or the proximal penile urethra. Straddle injuries compress the urethra against the symphysis pubis with possible rupture, therefore it is important to perform urethrography before attempting catheterization. A suprapubic catheter is the preferred option in this situation.

•   Inflammation: usually occurs in the anterior urethra, often from gonorrhoea, tuberculosis or non-specific urethritis.

• Neoplasia: develop as a result of malignant infiltration, but is rare.

Fig. Urethrogram: multiple strictures in the anterior urethra

 

Fig. Normal urethrogram. The smooth narrowing in the posterior and prostatic urethra is normal

BLADDER CARCINOMA

After prostatic carcinoma, the bladder is the commonest site of neoplastic involvement in the urinary tract. The tumour is usually a transitional cell carcinoma. Predisposing causes include:

•  industrial exposure to aromatic amines;

•  cigarette smoking;

•  chronic infection with Schistosoma haematobium (squamous cell carcinoma);

•  chronic inflammatory changes due to calculi (squamous cell carcinoma).

RADIOLOGICAL  FEATURES

Cystoscopy is mandatory in any patient suffering from haematuria. IVU is also often performed to assess the upper urinary tract with respect to:

•  degree of obstruction;

•  state of the ureters;

•  renal function;

• identifying other lesions as transitional cell carcinoma is often multifocal.

Demonstration of the bladder carcinoma is by either a filling defect in the contrast filled bladder or an irregular mucosal pattern on the postmic-turition bladder films. If the intravenous urogram shows ureteric obstruction, it signifies muscular involvement near the ureteric orifice rather than obstruction by a neoplastic mass compressing the ureter. CT or MRI are useful in pre-operative assessment of intramural and extramural spread, local invasion, lymph-node enlargement, and liver or lung secondary deposits.

A chest X-ray should always be performed to exclude lung secondaries.

TREATMENT

Depends on the staging:

•  Superficial tumours: Ta or TI can be successfully resected endoscopi-cally.

•  Invasion of bladder muscle: T2,T3a,T3b may be treated by endoscopic resection, partial or total cystectomy with radiotherapy or chemotherapy.

Invasion of surrounding organs: T4 into prostate, uterus etc. Need palliative radiotherapy or chemotherapy or palliative cystectomy with urinary diversion.

Fig. IVU: carcinoma of the bladder seen as a filling defect in the left bladder; note renal obstruction.

Fig. CT shows left bladder wall thickening and extension of the carcinoma beyond the bladder wall (arrows).

PROSTATIC ENLARGEMENT

The usual cause of prostatic enlargement is benign hypertrophy but some­times it may be due to carcinoma. Chronic retention secondary to outflow obstruction, as a result of prostatic enlargement, can lead to renal failure.

RADIOLOGICAL  FEATURES

•  Plain films. Prostatic calcification and calculi are common, seen as multi­ple fine-scattered densities projected above the symphysis pubis. Sclerotic secondary deposits from primary prostatic carcinoma may be visualized on a plain abdominal film.

•  Intravenous urography may show a large filling defect at the bladder base, residual urine, the presence of obstructive changes and bladder wall thick­ening.

•  Transabdominal ultrasound. Assesses upper urinary tract; it is more accu­rate than intravenous urography for residual urine.

•  Transrectal prostatic ultrasound. The scan is performed after the introduc­tion of the transducer into the rectum to assess the size and presence of localized masses. Differentiation between benign and neoplastic disease cannot be confidently made without a biopsy for histological analysis. Car­cinomas are commonest in the periphery of the gland where they are seen as a focal nodule or diffuse infiltration.

•  CT/MRI. Evaluates tumour spread beyond the prostatic capsule and tumour invasion into the bladder or rectum. MRI is proving the more precise technique.

•  Isotope bone scan. May demonstrate secondary deposits.

Fig. Plain film shows prostatic calcification above the symphysis pubis.

Fig. Transabdominal ultrasound visualizing the prostate gland (arrow). Transrectal scanning is more accurate.

 

TESTICULAR TUMOUR

Ultrasound is extremely effective in the evaluation of the normal testis and in recognizing a focal lesion; masses of only a few millimetres in diameter are accurately visualized. An abnormal echo lesion in the testis needs a biopsy for a definitive diagnosis.

•   Seminoma: comprise the majority of testicular tumours and appear as homogeneous well-defined low echo mass lesions, sharply demarcated from normal testicular tissue.

•   Teratoma: these have a mixed echo pattern and may be cystic or solid. The peak incidence of testicular tumours is between the ages of 25 and 35, with an increased risk in undescended testes. In the older age group, a tes­ticular mass is more likely to be metastatic, rather than a primary tumour. Tumour staging requires a CT thorax, abdomen and pelvis.

Fig. Ultrasound: hydrocele, an occasional manifestation of testicular tumour.

Fig. Ultrsound: localized altered echo pattern in testicular tumour (arrow).

 

RADIOLOGYCAL EXAMINATION OF  GENITAL TRACT

GYNAECOLOGY

Ultrasound

Ultrasound of the female pelvis is now the primary imaging in­vestigation in many gynaecological problems. These include the investigation of congenital anomalies, of pelvic masses and pelvic inflammatory disease, the monitoring of ovarian function and ovarian pathology, the assessment of uterine pathology, and the control of intrauterine contraceptive devices (IUCD).

Most cases are examined by transabdominal scanning, but transvaginal scanning can provide better detail in selected cases as can transrectal scanning in elderly patients.

IUCDs. These are readily identified by ultrasound as a strong linear echo or a row of punctate echoes within the uterine cavity, some­times with acoustic shadowing. Where the IUCD is not shown a plain abdominal X-ray is required to exclude the rare complication of migration of the device into the abdominal cavity.

Fig. IUCD (arrowed). Note acoustic shadowing (S).

Ovarian function. The normal ovaries can usually be identified as small ovoid structures lateral to the uterus and hypoechoic to the surrounding pelvic fat. They are largest in the postpubertal female when they reach 3×2 cm or more in size, but atrophy in the postmenopausal female. Post puberty, several tiny cysts may be seen in the peripheral zone of the ovary representing follicles.

During the menstrual cycle the development of a dominant follicle can be observed by ultrasound as it increases in size from less than 5 mm to as much as 20 mm in size. This takes place by day 14 when rupture occurs.

Enlarged ovaries with multiple cysts may be seen in the Stein-Leventhal syndrome (amenorrhoea, infertility, hirsutism and obesity). Multicystic ovaries may also be seen in anorexics and in athletes. They are also a feature of Pergonal stimulation in the treatment of infertility.

Fig. Pergonal ovary. Numerous large follicles. Moderate overstimulation.

PELVIC MASSES

Uterine fibroids are the commonest female tumour, occurring in 20% of females above the age of 30. They can be interstitial, submucosal or subserous in position and small or large in size. They can also undergo hyaline or cystic degeneration and they frequently calcify. The sonographic features are equally diverse but they usually enlarge the uterus giving it a bulbous fundus and an irregular or lobulated contour. A focal uterine mass may show hypo-or hyperechoic features. Calcification is markedly hyperechoic.

Uterine carcinoma, both endometrial and cervical, is best assessed by CT or MRI which are also valuable in staging. Primary diagnosis is rarely made by ultrasound but it can demonstrate the tumour mass and-help in staging and in monitoring the results of treatment.

Hydatidifbrm mole and the rarer choriocarcinoma show characteristic features at Sonography. The uterine cavity is occupied by a large echogenic mass which is homogeneous during the first trimester but develops small cystic cavities in the second trimester.

Ovarian masses are often cystic. They include cystadenoma, cyst-adenocarcinoma, dermoid, teratoma and other rare tumours. In young females, benign tumours predominate by 5 to 1, but in post menopausal patients the incidence of malignancy rises to reach 2 to 1.

Fig. Ovarian cyst with septa seen anteriorly.

 

Fig. The empty abdomen appearance caused by a huge cyst displacing the abdominal organs. Note aorta (A) and vertebral body (VB) are seen in horizontal section.

Cystadenomas at ultrasound usually appear as thin-walled cysts. These can become very large giving rise in extreme cases to the sonographically ’empty abdomen. The mucinous type are more likely to contain septations than the serous type. Cystadenocarcinomas are more likely to be complex cysts with solid components and ascites is often present.

Fig. Biloculated cystadenocarcinoma with a large solid component  = cystic components, solid component arrowed.

Fig. Cystadenocarcinoma of the left ovary with a solid component extending to the pelvic side wall. Deep extension and distant nodal metastatic spread are better seen by CT than by ultrasonography.

CT and MRI

CT is now widely used in the further assessment of pelvic and abdominal tumours and is particularly valuable in the staging of malignant tumours. MRI is probably more accurate than CT in the staging of gynaecological carcinomas, particularly cervical carcinoma.

Fig. Tumour infiltration (arrows) of the right pelvic side-wall, on a transverse T,-weighted spin-echo (SE 70/40) image, in a patient with carcinoma of the cervix treated by hysterectomy 6 months previously

Simple X-ray

Simple X-rays of the pelvis can be helpful in the diagnosis and differential diagnosis of some pelvic masses in the female. Fibroids often calcify and the calcification has a characteristic mottled irregular appearance on X-ray which is diagnostic.

Ovarian dermoids may show calcification in their wall or they may show dental structures which can be readily recognised by radiology. Occasionally, owing to their high fat content, a relative translucency within the tumour may be recognised. Tuberculous pyosalpinx may show characteristic calcareous debris outlining the lesion.

Apart from simple X-rays the only other X-ray technique still widely used for the investigation of gynaecological problems is salpingography.

Hysterosalpingography

Hysterosalpingography is most widely used in the investigation of sterility. The investigation is obviously contraindicated in the pres­ence of pregnancy, severe haemorrhage or active infection.

With water-soluble contrast media peritoneal spill from the tubes can be observed immediately by screening the salpingogram during injection. Salpingography is performed in the X-ray department and is best done by the radiologist and gynaecologist in cooperation. The radiologist observes the injection on an image intensifier and takes any appropriate pictures necessary.

Fig. Calcified fibroid

Fig.  Dental structures in a pelvic dermoid

Fig. Large calcified dermoid in the pelvis.

Fig.  Normal salpingogram, both Fallopian tubes fill and contrast is seen in the peritoneum. The uterine cavity is also outlined

 

Fig. Diagrammatic representation of important congenital abnormalities of the uterus.

Fig. Uterus bicornis bicollis.

The normal hysterosalpingogram shows the uterus as an inverted triangular shadow and the tubes as fine sinuous lines extending out from the cornual angles.

In cases of sterility normal appearances may be shown with a free spill into the peritoneum and a local mechanical cause may thus be excluded. In these normal cases the prognosis is fair and in one series about a third of the patients subsequently became pregnant. It has even been postulated that salpingography had a therapeutic effect in some of these patients by clearing adhesions. On the other hand the salpingogram may show a definite cause for sterility such as blockage of both tubes or the presence of bilateral hydrosalpinx. Congenital anomalies of the uterus such as bicornuate or infantile uterus may be seen, or grosser anomalies such as uterus didelphys may be diagnoses.

NORMAL UTERUS AND OVARIES

The uterus and ovaries are well visualized by a pelvic ultrasound scan. A more precise and detailed examination is obtained using a transvaginal probe.

•  Uterus: ultrasound assesses size, outline, position and myometrial abnormalities such as leiomyomas and congenital uterine anomalies.

•  Endometrium: this is seen as an echogenic linear area, the appearances varying through the menstrual cycle. It is poorly visualized in post­menopausal women due to atrophic changes and carcinoma may be sus­pected when there is abnormal thickening or configuration.

•  Endometrial cavity: ultrasound accurately delineates retained products of conception and may visualize polyps.

•  Fallopian tubes: generally not adequately seen, unless there is a hydrosalpinx.

•  Ovaries: appear as oval structures lateral to the uterus, being small and atrophic in postmenopausal women. Follicular development can be monitored using ultrasound.

•  Adnexa, cul-de-sac: detection of masses and free fluid.

Fig. Transabdominal scan demonstrating the midline uterus (f) and ovaries (-♦) on either side.

UTERINE FIBROIDS LEIOMYOMA

Fibroids are common tumours, resulting from benign overgrowth of smooth muscle and connective tissue.

RADIOLOGICAL  FEATURES

The following may be noted on ultrasound.

•   Calcification:also shown on plain films and computed tomography (CT).

•   Enlarged uterus, with a distorted outline.

•   Lobular or round masses of variable echogenicity being either myome­trial, pedunculated or subendometrial.

Magnetic  resonance  imaging  (MRI)  is  more  sensitive  at detecting fibroids (90%) than ultrasound (60%).

COMPLICATIONS

•  Infertility.

•  Dystocia.

•  Malignant sarcomatous degeneration (rare).

•  Cystic degeneration.

Fig. Calcification in a fibroid.

 

Fig. 9.3 Ultrasound examination demonstrating two large fibroids (arrows) in the uterus.

INTRAUTERINE CONTRACEPTIVE DEVICE

Ultrasound is a valuable aid in assessing the position of an intrauterine contraceptive device (lUCD), identified lying in the endometrial cavity as a linear echogenic structure. The commonest cause of non-visualization is, however, expulsion of the device. If not seen on ultrasound, a plain abdomi­nal film is recommended, as the lUCD may have perforated through the myometrium and be lying free in the abdominal cavity. Perforation is usually silent without symptoms and the lUCD can be removed by laparoscopy.

 

 

Fig. Perforation with IUCD seen lying over the right iliac bone (arrow).

 

 

Fig. Ultrasound: IUCD in the endometrial cavity.

FALLOPIAN TUBES OCCLUSION

Causes of occluded fallopian tubes include previous infection, peritonitis (especially from appendicitis) or tubal surgery. Radiological confirmation can be obtained by hysterosalpingography, the injection of contrast into the uterine cavity to assess the uterus and patency of fallopian tubes. Usually there is rapid filling of the fallopian tubes with free spillage of contrast into the peritoneal cavity, confirming tubal patency.

Fig. Hysterosalpingography: occlusion of the right fallopian tube and a left hydrosalpinx

POLYCYSTIC OVARIES

Polycystic ovaries are associated with chronic anovulation due to distur­bances of leuteinizing hormone (LH) and follicle stimulating hormone (FSH).

The classical clinical features that suggest polycystic ovary syndrome are obesity, hirsuitism, infertility and oligomenorrhoea (Stein-Leventhal syndrome). However, many women have biochemical abnormalities without these features, and present with menstrual irregularity.

Ultrasound may show marked ovarian enlargement, although they may be of a normal size. Multiple small immature follicles are noted, often lying in the subcapsular position.

Fig. Polycystic ovary: transvaginal scan demonstrating an enlarged ovary with multiple small cysts.

Fig. Benign ovarian cyst: thin walled simple cystic structure (arrow) seen adjacent to the uterus.

Ovarian cysts are common and they can attain sizes that can occupy most of the abdominal cavity.

RADIOLOGICAL   FEATURES

On ultrasound the typical appearances indicating a benign lesion are: thin walls; free of internal echoes; lack of internal septations.

Simple cysts ^6 cm should have a follow-up ultrasound. A large cyst may show on a plain abdominal film as a soft-tissue mass arising out of the pelvis. Complex cysts may be haemorrhagic or endometrioma.

CT and MRI are both accurate imaging modalities when ultrasound is equivocal or when malignancy is suspected.

TYPES   OF  BENIGN  CYSTS

•   Follicular cysts. These are unruptured graffian follicles. They resolve spontaneously and generally do not attain a size >6cm. Serial scans confirm resolution of these cysts.

•   Corpus luteum cysts. The corpus luteum normally degenerates after ovulation, but may persist, sometimes with internal haemorrhage.

•   Mucinous cystadenoma and serous cystadenoma are benign cysts with a malignant potential, a far more frequent occurrence in the latter.

OVARIAN CARCINOMA

Ovarian carcinoma is the commonest cause of death from female genital-tract cancer.

PRESENTATION

•  Asymptomatic discovery on routine examination.

•  Weight loss and anorexia.

•  Abnormal vaginal bleeding.

•  Pelvic abdominal mass or distension.

RADIOLOGICAL  INVESTIGATIONS

•  Plain abdomen; chest X-ray.

•  Ultrasound.

•  Intravenous urography (IVU).

•  MRI/CT for staging.

RADIOLOGICAL  FEATURES

•  Ultrasound is the most appropriate initial investigation and the diagnosis can be frequently made by this technique. Malignancy may be suspected in a pelvic mass if the following features are present: thick irregular septa-tions with nodules; thick wall with irregularity of the inner wall; mixed solid and cystic components; local invasion; ascites (although this may also be seen in benign lesions); liver metastases.

•  IVU is performed if there is suspicion of ureteric involvement.

•  MRI/CT are accurate in staging the tumour prior to resection.

COMPLICATIONS

•  Torsion: twisting on its pedicle interrupts the blood supply, initially venous then arterial. Results in severe pain when this complication arises.

•  Infection.

•  Rupture: pain and vomiting.

•  Haemorrhage into cyst.

MALIGNANT  OVARIAN  TUMOURS

•  Metastases: Krukenberg secondaries from mucus-secreting stomach or colon carcinoma.

•  Malignant cystadenocarcinoma.

Granulosa cell, theca cell, androblastoma, disgerminoma, teratoma.

Fig. Ovarian carcinoma: large mass seen arising out of the pelvis (arrows) and causing moderate ureteric obstruction.

Fig. Cystadenocarcinoma: ultrasound demonstrating a large cystic lesion with several internal septations.

OBSTETRICS

Ultrasound found its first major clinical usage in obstetrics and has made its greatest contribution in this field. It is now the vital technique for the monitoring of normal and abnormal pregnancy.

Early pregnancy (first trimester)

The normal non-pregnant uterus at transabdominal scanning is shown as an egg-shaped structure, larger at the fundus, and lying directly behind the distended bladder. All pelvic ultrasound examinations should be conducted with the bladder well distended, as this displaces gas-containing bowel and allows uninterrupted access of the ultrasound beam to the uterus lying behind the bladder.

In early pregnancy the uterus enlarges and a gestation sac can be identified as early as 5-6 weeks after the first day of the last menstrual period. Transvaginal scanning can identity the sac as early as 4 weeks. It appears as a cystic area with a rim of high intensity echoes. By 10 weeks the sac has enlarged to occupy most of the uterine cavity. The developing embryo or ‘fetal node’ can be identified from the 6th or 7th week and the fetal head at 14 weeks. Multiple pregnancy can also be identified at an early stage by the presence of two or more gestation sacs.

The fetal heart beat can be identified soon after the fetal node is seen and must always be looked for as evidence of a live fetus.

The crown-rump length of the fetal node can be measured accurately by electronic calipers between the 7th and 14th weeks of pregnancy and assessed against the normal standards. In a normal pregnancy the measurement can predict maturity with considerable accuracy. Gestation sac volume can also be measured by ultrasound but is less accurate in assessing maturity.

Fig. Early pregnancy. (A)^ongitudinal scan. 9 weeks menstrual age. The gestation sac is large at this stage and the fetus (fetal node) is shown as an oval collection of echoes within it. b = bladder. (B) Diagram of (A).

GESTATION: 6 WEEKS

Ultrasound can be performed to confirm and date pregnancy or to detect complications such as an ectopic pregnancy or threatened abortion. The earliest detection of the sac is at 5-6 weeks on a pelvic ultrasound scan, seen as a ring-shaped echo-free area in the uterine cavity. Gestation age can be estimated by sac volume and the fetal crown-rump length; fetal cardiac pulsation is visible at approximately 7 weeks.

Fig. Gestation at 6 weeks.

 

Transvaginal scanning produces a more detailed evaluation and both the gestation sac and cardiac pulsation are recognized earlier than with a transabdominal scan.

GESTATION: 16 WEEKS

Ultrasound is often used at this time to assess gestation age, fetal viability and fetal abnormalities.The placenta can be evaluated for its location and any accompanying abnormalities.

Fig. Gestation at 16 weeks.

Fetal parameters utilized for gestation age are:

•  biparietal diameter;

•  head circumference;

•  abdominal circumference;

•  femur length.

ECTOPIC GESTATION

Ectopic pregnancy arises from failure of a fertilized ovum to reach the uterine cavity with subsequent implantation in the fallopian tube. Rarely, implantation may occur in the ovary or peritoneal cavity.An increased risk of ectopic pregnancy exists with pelvic inflammatory disease, use of an IUCD and a previous history of tubal surgery or ectopic gestation.

RADIOLOGICAL  FEATURES

A normal ultrasound examination does not exclude an ectopic pregnancy, evaluation being more precise using transvaginal scanning. Some of the fea­tures below may be present:

•  absence of gestation sac in uterine cavity (with positive pregnancy test);

•  visualization of gestation sac or fetus outside the uterine cavity;

•  endometrial thickening;

•  free pelvic fluid;

•  adnexal mass.

The tubal pregnancy often ceases at 6-10 weeks either by tubal rupture or tubal abortion.

Abnormalities of early pregnancy

These include:

1.    Missed abortion

2.    Anembryonic pregnancy (blighted ovum)

3.    Live abortion

4.    Hydatidiform mole

5.    Ectopic pregnancy.

Missed abortion accounts for nearly half the cases of early preg­nancy failure. At ultrasound the fetal heart beat cannot be detected even with real-time scanning. It is important to realise that even with a dead fetus it is still possible to have a positive pregnancy test as the trophoblast can continue to function.

Fig. Anembryonic pregnancy. The uterus and sac are small for dates and no fetal node is identified

Anembryonic pregnancy is almost as common as missed abortion. The diagnosis is made in those pregnancies in which the gestation sac cannot be shown to contain a fetus either at ultrasound or in the aborted products of gestation. Apart from this absence of a fetal node and’fetal heart beat the gestation sac is ‘small for dates’ at ultrasound.

Live abortion is defined as early (before 12th week) or late (after 12th week). The early group may show a low gestation sac volume at ultrasound but appearances may be normal even a few days before abortion.

Hydatidiform mole is rare in Europe (about 1 in 2000 pregnancies). At ultrasound the uterus is large for dates. No fetal parts or fetal heart beat can be detected, and the uterus is full of multiple fine echoes. The patients have high gonadotrophic levels in the urine.

Ectopic pregnancy. This may be unruptured in which case the gestation sac is identified in an extrauterine location and a fetal node and fetal heart beat are identified within it, or it may be ruptured in which case the extrauterine sac is associated with a complex haema-toma mass. In both cases the uterus is enlarged and contains a mottled pattern but no gestation sac. Diagnosis of the adnexal mass can be difficult and in some cases may require laparoscopy.

Mid and late pregnancy (second and third trimesters)

18 to 20 weeks is a good time to perform routine examination of pregnancy by ultrasound. This should document:

1.    Fetal number

2.    Fetal life (heart beat)

3.    Fetal position

4.    Gestational age (see below)

5.    Abnormalities of the fetus (see below)

6.    Placental location

7.    Amniotic fluid – normal, polyhydramnios or oligohydramnios.

Fetal age

Various parameters can be used for assessing fetal age. The measure­ments are then compared with standard charts based on large series. The measurements used are:

1.    Biparietal diameter of the skull (BPD)

2.    Femoral length (FL)

3.    Head circumference (HC)

4.    Abdominal circumference (AC).

Crown-rump length is also used in the early stages of pregnancy (up to 9 or 10 weeks) and before the other parameters are readily usable.

The measurements listed are accurate ± 1-2 weeks in the first and second trimester but only ± 2-3 weeks nearer term.

The BPD is perhaps most widely used and is measured on a transverse axial image of the skull at its widest diameter.

GENETIC SCREENING

Amniocentesis, chorionic villous sampling and fetal blood sampling are invasive procedures which are being increasingly used for genetic screening. They all require ultrasound control for success, and carry a risk of fetal loss or damage.

Maternal serum fetoprotein (MSAFP) screening is a useful non­invasive test which can be helpful in selecting patients for the more invasive procedures at 15 to 20 weeks

FETAL ANOMALY

Many congenital abnormalities of the fetus caow be recognised in utero by ultrasound screening. In many cases these can be diagnosed sufficiently early for therapeutic termination to be a realistic possibility where this is considered desirable.

A vast number of fetal abnormalities can be detected by ultrasound some of which include:

•  central   nervous   system:   anencephaly,   spina   bifida,   meningocele, encephalocele and hydrocephalus;

•  chest: cardiac anomalies and pulmonary hypoplasia;

•  gastrointestinal tract: duodenal atresia;

•  renal tract: hydronephrosis, polycystic disease;

•  skeletal: dwarfism.

Neural tube defects. These include the fatal condition of anencephaly  and the various forms of spina bifida ranging from severe lumbar myelomeningocele to potentially correctable meningocele. Encephalocele, hydrocephalus and various congenital anomalies of the brain are all identifiable.

Heart. A four-chamber view of the fetal heart can be obtained from about 18 weeks onwards. Not only can the cardiac chambers and great vessels be measured but dysrhythmias and valvular lesions can be diagnosed and the latter quantified using colour Doppler. Thus many forms of congenital heart disease and other cardiac anomalies caow be diagnosed in utero.

Fig. Fetal heart: subcostal four-chamber image. S = spine, ra = right atrium, la = left atrium, rv = right ventricle with moderator band, lv = left ventricle

Congenital diaphragmatic hernia (CDH) is a rare but serious condition which can also be recognised in utero as can other rare congenital lung anomalies.

Abdomen. Abdominal wall defects leading to omphalocele or gastroschisis have been diagnosed at fetal ultrasound as have duodenal atresia, ascites and other anomalies. Lesions of the GU system recognised include the fatal bilateral renal agenesis (Potter’s syndrome or renofacial dysplasia), infantile renal polycystic disease and multi-cystic dysplastic kidneys. Fetal hydronephrosis, unilateral and bilateral, is also diagnosable.

Hydrops fetalis due to isoimmunisation from fetomaternal blood group incompatibility is now rare since it can be treated by Rhimmune globulin therapy. Most of the cases seeow are associated with non-immunological causes including a wide variety of fetal congenital and otheTabnormalities.

The sonographic features include:

1.    Polyhydramnios

2.    Increased placental thickness

3.    Skin thickening

4.    Ascites, pleural and pericardial effusion.

THE PLACENTA

The placenta is easily identified by ultrasound and its site is always noted at routine examination. Localisation is particularly important in:

1.    Antepartum haemorrhage (placenta praevia, abruptio placentae)

2.    Amniocentesis.

With amniocentesis, ultrasound control enables the needle to be inserted into a pool of amniotic fluid without traversing the placenta or causing damage to the fetus.

Mil

There is as yet no experimental or other evidence that MRI is harmful to the fetus but both the National Radiation Protection Board in the UK and the Food and Drugs Administration in the USA recommend that it should not be used in the first trimester.