Residency · Residency · Urology
Urogenital Tuberculosis and Schistosomiasis
Introduction
Urogenital tuberculosis (UGTB) and schistosomiasis are two infectious diseases of global importance that have significant urologic manifestations. UGTB represents the second most common form of extrapulmonary tuberculosis, while schistosomiasis affects over 200 million people worldwide. Both conditions can lead to irreversible structural damage within the urinary tract if they are not diagnosed and treated promptly. Urologists working in endemic regions or caring for immigrant populations must maintain a high degree of clinical suspicion for these diseases to ensure early detection and management.
Urogenital Tuberculosis
Epidemiology
Urogenital tuberculosis accounts for approximately 15-20% of all extrapulmonary tuberculosis cases. It is most prevalent in regions with a high burden of tuberculosis, including Southeast Asia, Sub-Saharan Africa, and Eastern Europe. The disease typically manifests 5 to 25 years after the initial pulmonary infection. Its incidence is rising, particularly among immunocompromised individuals such as those co-infected with HIV.
Pathophysiology
The causative organism, Mycobacterium tuberculosis, reaches the genitourinary tract primarily through hematogenous spread from a primary pulmonary focus. The kidneys are the initial target organ, where bilateral cortical granulomas form during the initial bacteremia. Disease progression occurs when host immunity declines, allowing caseating granulomas to erode into the collecting system. The infection then descends sequentially, affecting the ureter, bladder, and genital organs. The pathological hallmarks of UGTB include caseous necrosis, granuloma formation, fibrosis, and calcification.
Clinical Presentation
UGTB often presents insidiously with nonspecific symptoms, earning it the nickname "the great mimicker." The hallmark clinical finding is sterile pyuria, which refers to the presence of white blood cells in the urine without bacterial growth on routine cultures. Patients may experience irritative voiding symptoms such as frequency, dysuria, and urgency. Hematuria, either gross or microscopic, is common. Flank pain may arise due to ureteral strictures and hydronephrosis. In males, genital tuberculosis can present with epididymal swelling resembling a "cold abscess," scrotal sinus tracts, and a beaded vas deferens. Constitutional symptoms like fever, weight loss, and night sweats occur in only 20-30% of cases.
<image>Pathological specimen and corresponding CT scan of a kidney affected by urogenital tuberculosis showing parenchymal destruction with caseous cavities, cortical thinning, and dystrophic calcification (putty kidney or autonephrectomy)</image>
Diagnosis
Diagnosis relies on a combination of laboratory and imaging studies. Urinalysis typically reveals persistent sterile pyuria and acidic urine. Acid-fast bacilli (AFB) smear and culture require three consecutive early-morning urine specimens, with cultures grown on Lowenstein-Jensen medium taking 6-8 weeks. Urine PCR testing using GeneXpert MTB/RIF allows rapid detection of M. tuberculosis with a sensitivity of 85-95% and near 100% specificity. Tuberculin skin tests (PPD) and interferon-gamma release assays (IGRAs) indicate prior TB exposure but do not confirm active disease. Imaging findings on intravenous urography (IVU) or CT urogram may show moth-eaten calyces, infundibular strictures, phantom calyx, ureteral beading, and a contracted "thimble bladder." Plain radiographs can reveal dystrophic calcifications consistent with autonephrectomy or "putty kidney." Chest X-rays demonstrate evidence of prior or active pulmonary tuberculosis in about half of patients.
Management
The cornerstone of treatment is first-line anti-tuberculous therapy (ATT), which follows a standard six-month regimen. The intensive phase lasts two months and includes isoniazid, rifampicin, pyrazinamide, and ethambutol (HRZE), followed by a four-month continuation phase with isoniazid and rifampicin (HR). Corticosteroids may be considered during ATT to reduce fibrosis and prevent ureteral strictures. Ureteral stenting is indicated for obstructing ureteral strictures and should be placed early in the treatment course. Surgical interventions are reserved for complications: nephrectomy is performed for non-functioning kidneys (autonephrectomy), ureteral reimplantation or Boari flap procedures address distal ureteral strictures, augmentation cystoplasty is used for contracted thimble bladder, and epididymectomy is indicated for refractory epididymal tuberculosis.
Schistosomiasis (Bilharziasis)
Epidemiology
Schistosomiasis is caused by trematode flukes, with Schistosoma haematobium being the primary species responsible for urogenital disease. It is endemic in Sub-Saharan Africa, the Middle East, and parts of Southeast Asia. Transmission occurs through contact with freshwater containing infected snails, specifically Bulinus species, which serve as the intermediate host. Over 200 million people are infected worldwide, with approximately 700 million at risk.
Life Cycle and Pathophysiology
The infective cercariae penetrate intact skin during exposure to contaminated freshwater. They mature into adult worms within the vesical venous plexus. Female worms deposit eggs in the bladder wall and distal ureters. The host immune response generates granulomatous inflammation around the eggs, leading to mucosal ulceration, polypoid lesions, and fibrosis. Chronic infection results in bladder wall calcification, ureteral strictures, and hydronephrosis. There is a strong association between chronic schistosomiasis and squamous cell carcinoma (SCC) of the bladder.
Clinical Presentation
The acute phase, known as Katayama fever, occurs weeks after exposure and is characterized by fever, urticaria, and eosinophilia. Chronic urogenital disease presents with terminal hematuria, which is the classic symptom. Patients may also experience dysuria, urinary frequency, and suprapubic pain. Obstructive uropathy can develop due to ureteral fibrosis. Imaging may reveal sandy patches and calcified bladder walls. Female genital schistosomiasis manifests as vulvar or cervical granulomas and can cause infertility.
<image>Cystoscopic image showing multiple sandy patches and granulomatous lesions on the bladder mucosa in chronic urogenital schistosomiasis, with annotations indicating calcified ova deposits and surrounding inflammatory tissue</image>
Diagnosis
Diagnosis is established by detecting S. haematobium eggs with terminal spines in urine samples, optimally collected between 10 AM and 2 PM. Serologic tests such as ELISA for schistosomal antibodies are useful in travelers from non-endemic areas. Peripheral eosinophilia is often present on complete blood count. Cystoscopy reveals sandy patches, granulomas, polyps, and ulceration of the bladder mucosa. Biopsy specimens show granulomas with embedded schistosome ova. Imaging studies include plain radiographs demonstrating linear bladder wall calcification, which is pathognomonic, ultrasound showing bladder wall thickening and hydronephrosis, and CT or IVU revealing ureteral strictures and bladder contraction.
Management
Praziquantel at a dose of 40 mg/kg, given as a single dose or split into two doses, is effective against all Schistosoma species. Repeat treatment may be necessary in heavy infections. Surgical management addresses complications such as ureteral strictures, which may require ureteral reimplantation, and contracted bladder, which may necessitate augmentation cystoplasty. Radical cystectomy is indicated for schistosomal squamous cell carcinoma of the bladder. Mass drug administration programs in endemic areas are critical for disease control. Patients with chronic schistosomiasis require long-term surveillance for bladder cancer.
<image>Comparison diagram showing the life cycles of Mycobacterium tuberculosis (hematogenous spread to kidneys) and Schistosoma haematobium (cercariae penetration, maturation in vesical venous plexus, egg deposition in bladder wall) with key urologic manifestations highlighted at each stage</image>
Key Clinical Pearls
Sterile pyuria should always prompt suspicion for urogenital tuberculosis, and it is essential to send three early-morning urine specimens for acid-fast bacilli testing. The introduction of GeneXpert MTB/RIF has revolutionized rapid tuberculosis diagnosis due to its high sensitivity and specificity. Schistosomiasis-associated bladder cancer is typically squamous cell carcinoma, which contrasts with the transitional cell carcinoma commonly seen in non-endemic populations. Linear bladder wall calcification on plain radiographs is pathognomonic for schistosomiasis. Both urogenital tuberculosis and schistosomiasis can cause a contracted "thimble bladder" that may require augmentation cystoplasty. In cases of suspected UGTB, chest imaging should always be obtained to evaluate for concurrent pulmonary disease.
References
- Figueiredo AA, Lucon AM, Srougi M. Urogenital tuberculosis. Microbiol Spectr. 2017;5(1):TNMI7-0015-2016.
- Colley DG, Bustinduy AL, Secor WE, King CH. Human schistosomiasis. Lancet. 2014;383(9936):2253-2264.
- Merchant S, Bharati A, Merchant N. Tuberculosis of the genitourinary system — urinary tract tuberculosis: renal tuberculosis. Part I. Indian J Radiol Imaging. 2013;23(1):46-63.
- Mostafa MH, Sheweita SA, O'Connor PJ. Relationship between schistosomiasis and bladder cancer. Clin Microbiol Rev. 1999;12(1):97-111.
