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GENITOURINARY TRACT IMAGING Table of Contents   
Year : 2002  |  Volume : 12  |  Issue : 2  |  Page : 239-244
Genitourinary biharziasis : A review


Department of Radiology, L.T.M. General Hospital , Sion, Mumbai-400022, India

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Keywords: Bilharziasis, Schistosoma Haematobium, Schistosomiasis, Urinary bladder calcification, Ureter calcification

How to cite this article:
Merchant S A, Amonkar P P. Genitourinary biharziasis : A review. Indian J Radiol Imaging 2002;12:239-44

How to cite this URL:
Merchant S A, Amonkar P P. Genitourinary biharziasis : A review. Indian J Radiol Imaging [serial online] 2002 [cited 2019 Jun 16];12:239-44. Available from: http://www.ijri.org/text.asp?2002/12/2/239/28455
Bilharziasis is probably one of the oldest diseases known to mankind. In 1910, Ruffer discovered bilharzial ova in the kidneys of mummies dating

back to 1090 B.C. Historians of medieval Egypt told stories of a disease which made the men of Egypt "menstruate like women". Theodore Biharz discovered the causative organism in 1951[1].

INCIDENCE: The disease is estimated to affect 8% of the world population [2]. It has become endemic in most of Africa, the southern tips of Europe, Western Asia and the east coast of Japan [1]. Geographic differences in the overall frequency and severity of the lesions has been noted with the severest cases being seen in Egypt [3]. The disease can spread to non-endemic areas because of the great increase in foreign travel, especially due to the ease of air transportation [1],[2]. American soldiers posted to these endemic areas have often been affected by this disease [1].

AGE AND SEX: Bilharziasis can occur at any age, studies have shown patients ranging from 6 to 70 years [3],[4]. Males are affected much more commonly than females, probably because of their greater mobility [1],[5].

LIFE CYCLE OF S. HAEMATOBIUM: The definitive host for S. haematobium is man, whereas the intermediate host is the fresh water snail. Infection is contracted by humans when they come in contact with infected water. The larval forms of Schistosoma, called cercariae can penetrate unbroken skin directly [5]. These enter a peripheral venule or lymphatic ductule [1] and go via the right heart - lungs - left heart to reach the systemic circulation. They reach the liver and mature there into the adult forms.

The adult worms travel against the blood stream and migrate into the inferior mesenteric vein. The eggs are seen in the veins around the distal third of the ureter, the vesicoprostatic venous plexus and the middle rectal veins. The vesical plexus however shows the greatest number and it is here that the eggs are laid [1]. The eggs are laid in a chain of approximately twenty, positioned such that their spines engage the vessel wall [1],[5]. These enter the bladder wall and then the bladder cavity and escape out via urine. On gaining access to water, they penetrate into the soft tissues of the snail [5]. Here they differentiate into the cercariae which leave the snail and enter the water, to start a new cycle.


   Pathology Top


Schistosomal eggs deposited in body tissues act like foreign proteins and have an irritative effect leading to the formation of a pseudo-tubercle around each egg ("bilharzioma") [1],[5]. The nodules are initially composed of eosinophils, monocytes, lymphocytes and giant cells. The disease can be divided into acute and chronic stages [4]. These have also been designated as hyper-plastic or hypoplastic [1].

(1) ACUTE STAGE: The disease usually starts in the trigone and the base of the bladder with submucosal granulomas. The overlying epithelium is hyperplastic and in severe cases a pseudopapillary appearance is seen [4]. The epithelial hyperplasia can extend into the submucosa and can produce cystitis cystica and ureteritis cystica, seen as polypoid defects on the bladder film [1],[4]. Hyperplastic changes are thought to predispose to squamous metaplasia and the development of a squamous cell carcinoma [1],[6].

(2) CHRONIC STAGE: The cellular reaction associated with bilharziomas induces fibrosis with a varying degree of severity [1],[5]. Calcification of the dead ova sets in as the fibrous tissue kills the incarcerated organisms [1]. This calcification takes characteristic forms which are described below. Schistosomiasis classically involves the bladder and the lower ureters [4], as opposed to tuberculosis which initially affects the kidneys and then spreads downwards via the ureters [7].

Severe fibrosis contracts the bladder and the ureter may be turned into an inelastic fibrous tube with stricture formation, with the inevitable development of back pressure changes [1]. The final and dreaded complication is the development of malignancy, usually squamous cell carcinoma. Malignant degeneration is estimated to account for 16% of the mortality in this disease [2].

RENAL involvement in bilharziasis is usually secondary to vesicoureteral involvement and consists of formation of renal calculi and development of hydro or pyonephrosis secondary to ureteral obstruction [1].

URETHRAL bilharziasis is in the form of polyps in the fossa navicularis, periurethral abscesses and perineal or scrotal fistulae [1]. Urethral strictures are not very common, except in long standing cases.

GENITAL ORGANS may also be involved by bilharziasis. Granulomatous sclerosis and fibrosis involve the prostate and seminal vesicles and rarely can involve the epididymis, spermatic cords and testes. Prostatic involvement by bilharziasis leads to an initial enlargement in the gland, which is followed by fibrosis and shrinkage. Retention cysts can form, which can get infected and lead to abscesses [1]. The seminal vesicles may get enlarged and may calcify. The ducts may become dilated and show hard, granulomatous masses.


   Imaging modalities Top


THE PLAIN FILM

The classic finding on the plain film is the presence of bladder wall calcification (6), though true calculi have also been reported. Worldwide, Schistosoma haematobium is the commonest cause of bladder wall calcification, an association well known to most radiologists [2],[6]. It comprises upto 56% of known bladder calcification [2] [Figure1],[Figure - 2],[Figure - 3].

BLADDER WALL CALCIFICATION: Urinary bladder wall calcification has relatively few etiologies [6]. The six most important causes of bladder wall calcification include: bilharziasis, primary carcinoma of the bladder, alkaline encrustation cystitis, amyloidosis, cyclophosphamide induced cystitis and tuberculosis [6]. A combination of history, clinical examination, appropriate laboratory studies and radiographic imaging of the bladder and the urinary tract will usually give the correct diagnosis [6].

Four patterns of calcification are recognized in bilharziasis [4],[6] Umerah et al [4] found the familiar linear rim type of calcification in 63%, a wavy linear calcification in 18%, a homogenous opacity in the bladder in 6% and a "cumulus cloud" appearance in 12%. This was often associated with 'tram line" calcification in the lower ureters, involving the left ureter more commonly than the right.

Bladder calcification has been classified by Jorulf et al [2] into three grades, according to severity, from Grade I to Grade III. Grade I calcification on the plain film involves upto 25% of the bladder circumference while Grade III involves the entire bladder circumference. On CT, Grade I calcification corresponds to involvement of upto 25% of the bladder circumference on any scan, while Grade III corresponds to involvement of the entire bladder circumference on any scan. Grade II is intermediate between Grade I and Grade III.

Calcification has been described in 50-63%of patients suffering from bilharziasis in various series [4],[6]. With the advent of CT, a higher percentage can be expected as even minor degrees of calcification can be picked up accurately. In the study of 20 patients done by Jorulf et al [2], calcification was seen in all patients on CT but only in 13 cases on plain films [2]. The degree of calcification roughly correlates with the number of eggs deposited [2],[6]. The bladder may be so heavily calcified that it can give the appearance of a cystogram on the plain film ! [1].

The calcification may initially be seen as a linear opacity paralleling the pubic bone. With further calcium deposition, the classic linear rim type of calcification is seen to encircle the bladder in the form of a continuous line [6]. Disruption in the continuity of this line indicates squamous metaplasia in the bladder, which is a well known complication secondary to the schistosomal irritation [6]. At times the calcification can be wavy and this simulates a post micturition film [4]. Massive calcification of the trigone, when seen en face has a diffuse flocculent pattern, which has been likened to a "cumulus cloud".

Primary carcinoma of the bladder can give rise to four types of calcifications: stippled, coarse (flocculent), punctate (finely stippled) and linear or curvilinear. Of these, the stippled calcification is seen in papillary tumours with low grade invasiveness and therefore show a better prognosis [6]. Calcification is most common in transitional cell and squamous cell carcinomas [6]. The calcification is dystrophic in nature and occurs as encrustation on the surface of the tumour. Only rarely is the calcification intratumoral [6].

As distinct from renal tuberculosis, tuberculosis of the bladder is rarely associated with calcification. When present, it is speckled or curvilinear and is usually associated with extensive renal and ureteric calcification [7].

Both alkaline encrustation, as well as cyclophosphamide induced cystitis show a circumferential curvilinear calcification [6]. Alkaline encrustation cystitis is usually seen following Gram negative cystitis, particularly Proteus species. These organisms convert urea to ammonia by elaborating the enzyme urease and this results in the formation of markedly alkaline urine, which causes precipitation of calcium salts [6]. An already devitalized bladder is susceptible to deposition of this calcium and this results in alkaline encrustation cystitis.

In addition to cyclophosphamide cystitis, erythema multiforme, radiation therapy and severe infectious cystitis due to any cause can also cause bladder calcification [6].

Calcification due to amyloidosis is very rare and the case seen by Pollack et al [6] showed a nodular or coarsely granular calcification associated with linear calcification in the distal part of the ureters. The cause is unknown but is thought to be due to amyloid deposition in the blood vessels of the tunica propria of the bladder and ureter causing ischemic atrophy of this layer, with subsequent dystrophic calcification. Pollack et al state that in bilharziasis, the submucosal calcification gets obscured by intraluminal contrast while in amyloidosis, a thin layer of uncalcified mucosa is seen between the intraluminal contrast and the submucosal calcification.

Ureteral calcification has been graded by Jorulf et al [2] into three grades of increasing severity, from Grade I to Grade III. Grade I calcification on the plain film consists of a dotted or "single line" pattern, less than 2 cm in length. Grade III calcification implies a "double line" pattern, at least 4 cm in length. On CT, Grade I calcification implies partial and Grade III total (circiular) calcification of the ureteric wall. Grade II is intermediate between Grade I and Grade III. Calcification is rare in the upper ureter and the pelviureteric junction [1]. Calcified papillomas may be seen in the lower third of t he ureter and may be difficult to differentiate from ureteric calculi, which can also occur commonly [1].

Seminal vesicle calcification may be identified as a classic mulberry shaped calcification on the plain film. Jorulf et al [2] classified seminal vesicle and prostatic calcification into three grades, similar to the ureteric calcification. Grade I consisted of a single calcific deposit while Grade III consisted of bilateral seminal vesicle calcification or circumferential calcification in the prostate. Grade II is intermediate between Grade I and Grade III


   The intravenous urogram Top


(A) THE BLADDER

The commonest finding is an irregular, contracted bladder wall with coarse mucosal folds [1],[2]. In some cases, large, irregular, polypoidal filling defects are seen in the bladder wall which may be due to the hyperplastic lesions seen in the early stages of the disease [4] or due to the development of carcinoma in the late stages [1].

Bilharziasis of the bladder though generalized is severest in the region of the trigone and when advanced, causes shortening of the trigone in all dimensions as also shortening of the supramontanal part of the posterior urethra. This fibrosis of the bladder neck leads to outlet obstruction and can contribute to vesico-ureteric reflux. Rarer causes of bladder neck obstruction in bilharziasis include papillomas blocking the bladder neck and prostatic fibrosis involving the bladder neck [1].

Elevation of the base of the bladder due to schistosomal prostatitis is often seen and may even be seen in children [1]. Vesical diverticuli have been reported [4] and vesical calculi are common [6].

Von Lichtenberg et al [8] and Young et al [3] have frequently observed ureterectasis without a demonstrable luminal obstruction which suggests that aperistalsis or functional incoordination is the cause of the dilatation. Applying the same principle, since bilharziasis commonly involves the region of the trigone, the resulting disorganization of the detrusor function could account for the frequent findings of postvoid residual urine and therefore for the increased incidence of urinary tract infections in such patients. The post void residue is also contributed to by vesico-ureteric reflux.

CARCINOMA is a common and feared complication of bilharziasis. It tends to occur at an earlier age, often seen in patients from 20 to 40 years of age and is seen more commonly in males [1]. These are squamous cell carcinomas and are found most commonly on the anterior wall of the bladder [2]. They are also seen on the lateral and posterior wall and the vault of the bladder [1]. The trigone is rarely involved [1],[4] Multiple tumors are seen in 25% of cases [2].

(B) THE URETERS

Ureteric involvement has been reported in upto 65% of cases [2]. The following changes are seen in the ureters:

(1) Dilatation: As mentioned above, ureterectasis is a common manifestation. The ureters can show a generalized or segmental dilatation (4). Kinks may be present and extrinsic impressions like those of vessels may be more prominent. The ureter may be so dilated that it has been compared to a loop of intestine [1].

(2) The "cow horn" deformity: Trigonal fibrosis results in medial and cranial displacement of the terminal part of the ureter, which has the appearance of a cow's horn [4]. This deformity was seen in 61% of patients in the study carried out by Umerah et al [4]. Catheterization of the ureters becomes very difficult in these cases [4].

(3) Ureteric stasis with decreased peristalsis in the ureter: Umerah et al [4] noted that the outlines of the ureters did not alter on serial films taken after release of compression. Hypotonia or even aperistalsis of the ureters was seen on fluoroscopy, which showed an improvement on changing the position of the patient to prone or upright (4). Jorulf et al also reported decreased ureteric contractions (three or less per minute) [2]. Young et al [3] have observed that the left ureter is involved more commonly than the right, with greater frequency of calcification and stenosis. They have also observed that younger patients tend to have polypoidal filling defects while calcified lesions are more commonly seen in older patients.

(4) A "snake head" appearance of the terminal part of the ureter, just before it enters the bladder wall is considered pathognomonic of the disease [1],[4]. It is due to a stricture of the intramural ureter [1].

(5) Vesicoureteric reflux can be present in one third of cases [1]. The cause for it is not well understood but various theories have been postulated, such as: (a) fibrosis of the lower end of the ureter causing it to become rigid and therefore compressible by the detrusor, which promotes reflux (b) stricture of the lower end of the ureter causing destruction of the normal valvular mechanism that prevents reflux. (c) myometrial fibrosis causing it to lose its function as an actively contracting tissue and therefore the lower end of the ureter cannot be effectively compressed [1].

(6) Ureteral strictures in bilharziasis [Figure - 4],[Figure - 5],[Figure - 6] have been classified into 3 types [1]. In order of decreasing frequency they are: annular, spindle shaped and "Makar's stricture". The last is named after N. Maker of Egypt, who first described it and is typically seen at the level of L3 verterbra. It is therefore also called as "third lumbar ureteral stricture" [1]. This is usually associated with a lot of dilatation and tortuosity of the ureter proximal to the stricture, along with hydronephrosis and eventual atrophy of the kidney. Strictures lead to hydronephrosis, secondary renal and ureteric calculi and atrophy of the kidney.

(7) Secondary ureteral calculi can be present [Figure - 6][1]. Using CT, distinction can be made between punctate ureteral wall calcifications and tiny intraluminal calculi [2].

(8) A "beaded" ureter may result due to multiple strictures in the lower part of the ureter. This can cause confusion with tuberculosis. However, calcification of the ureter is rare in TB and if present, is associated with renal calcification. In schistosomiasis of the ureter, calcification is seen in the majority of cases and is also associated with bladder calcification while renal calcification is very rare. Also, TB causes thickening and rigidity of the ureter, so that a straightened and shortened ureter is seen, whereas bilharziasis causes dilatation, lengthening and a marked tortuosity of the ureter.

(9) Multiple polypoidal filling defects can be seen in the ureter [4]. These can be either due to non calcified schistosomal granulomas or due to hyperplastic epithelium leading to ureteritis cystica [1] [Figure - 5].

(10) Medial deviation of the ureter associated with straightening of its lumbar part may be noted [4].

(C) THE URETHRA

The prostatic urethra is usually normal except for occasional findings of some hypertrophy of the verumontanum or extravasation of contrast into dilated prostatic ducts. The anterior urethra may reveal multiple fistulous tracts passing to the perineum. These usually arise from the bulbous urethra which is often irregular and narrowed [1]. It may be compressed by extrinsic inflammatory masses. Long segment penile urethral strictures and secondary urethral calculi may also be seen. These may be seen as radiolucent defects in the contrast filled urethra. The other differential for this type of appearance is the presence of urethritis cystica [1]. The two can however be distinguished by the fact that urethritis cystica is a submucosal pathology and therefore the lucencies are never totally surrounded by contrast but are seen to be in relation to the urethral wall. Calculi on the other hand lie freely within the urethral lumen and are totally surrounded by contrast [1].

(D) SEMINAL VESICLES AND EJACULATORY DUCTS

Seminal vesicular calcification has already been described, Seminal vesiculography reveals dilated seminal vesicles with ill defined borders [1]. Filling defects may be seen in the seminal vesicles due to granulomatous masses [1]. The ejaculatory ducts are patent and are of normal appearance and this differentiates the condition from malignancy in which the ejaculatory ducts are stretched, narrowed and obstructed [1].

 
   References Top

1.Hartman GW, Segura JW, Hattery RR, Infectious diseases of the genitourinary tract. In: Witee DM, Myers GH Jr, Utz DC eds. Emmett's clinical urography, 4th ed. Philadelphia. Saunders, 1977:921-945.  Back to cited text no. 1    
2.Jorulf H, Lindstedt C. Urogenital schistosomasis: CT evaluation. Radiology 1985; 157:745-749.  Back to cited text no. 2    
3.Young SW, Khalid KH, Farid Z, Mahmoud AH. Urinary tract lesions of Schistosoma hematobium. Radiology 1974; 111:81-84.  Back to cited text no. 3  [PUBMED]  
4.Umerah BC. The less familiar manifestations of schistosomiasis of the urinary tract. Br J of Radiology 1977; 50:105-109.  Back to cited text no. 4  [PUBMED]  
5.Chatterjee KD. Phylum In: Chatterjee KD ed Parasitology. Chatterjee Medical Publications, Calcutta, 1980.  Back to cited text no. 5    
6.Pollack HM, Banner MP, Martinez LO, Hodson CJ. Diagnostic considerations in urinary bladder wall calcification. AJR 1981;136:791-797.  Back to cited text no. 6  [PUBMED]  
7.Merchant SA. Tuberculosis of the Genitourinary System. Ind J Radiol Imag 1993; 3: 253 - 274.  Back to cited text no. 7    
8.Von Lichtenberg F, Edlington GM, Nwabuebo I et al , Pathological effects of schistosomasis in Ibadan, Western State of Nigeria: Pathogenesis of lesions of the bladder and ureters. Amer J Trop Med Hyg 1971; 20: 244 - 254.  Back to cited text no. 8    

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Correspondence Address:
S A Merchant
Department of Radiology, L.T.M. General Hospital , Sion, Mumbai-400022
India
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Source of Support: None, Conflict of Interest: None


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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6]

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