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Q1: What is the initial diagnosis?
Enterovesical fistula secondary to bladder carcinoma complicated by urinary tract infection.
Common causes of enterovesical fistula are1:
Diverticular disease of colon
Granulomatous bowel disease
Iatrogenic (for example, radiation therapy)
Clinical symptoms and signs are varied, mainly urinary tract infection (100%), pneumaturia (66%), and faecaluria (50%).2 Awareness of the possibility of an enteric origin of recurrent urinary tract symptoms should help prevent the long delays in diagnosis.3
Cystoscopy is regarded as the most useful diagnostic procedures in detecting fistula.4 Other modes of investigation are barium enema, cystography, colonoscopy, and computed tomography.1 2 In this case computed tomography distinctly (see p 122) showed (A) gas in the bladder (B) mass involving the bladder.
Treatment depends on the aetiology, localisation, and the patient's general condition. Commonly used technique is resection of the fistulous tract and the compromised intestinal segment, followed by repair of the bladder.4 The procedure can be performed as a single stage when the aetiology is diverticular or granulomatous bowel disease. Staged repairs are more judicious in patients with a large intervening pelvic abscess or those in whom advanced malignancy or radiation changes are present.1 Insertion of colonic stent, laparoscopic repair,5 and use of human fibrin glue for a recurrent fistula have also been described in the literature.
Q2: What and how common are the histological findings?
Unexpectedly, pathological assessment showed that the fistula was formed by two distinct primaries: adenocarcinoma from the colon and transitional cell carcinoma from the bladder. Note fig 2 (see page 122): (A) colonic adenocarcinoma and (B) poorly differentiated transitional cell carcinoma.
Malignancy is a known cause (35%–66%)2 4 of enterovesical fistula. The latter is most commonly vesicosigmoidal by location (50%).4 In this case the site of fistula was between dome of the bladder and sigmoid colon in deed. However, occurrence of two unrelated primaries of adjacent organs at the same site, which collided to form a fistula, was an extremely rare coincidence. We have not found any published reports of a similar nature, which makes this case unique.
Q3: What is the prognosis?
When the fistula is of malignant origin, the long term prognosis remains poor, as it is for any colonic (or bladder) carcinoma extending beyond the serosa and involving a contiguous organ. Fistulas secondary to radiation necrosis and recurrent tumour have an extremely poor outlook. Patients with fistulas due to diverticular disease (and to a lesser extent, Crohn's disease) can look forward to complete correction with low morbidity and mortality.3
This patient sadly died eight months after the operation from distant metastases.
Malignant vesicosigmoidal fistula due to collision between two distinct primary tumours arising from the colon and bladder respectively.