Enterovesical Fistula

Enterovesical fistula is an abnormal communication between the bowel and the bladder. Colovesical fistula, mostly from the sigmoid colon, makes up about 65 to 70%.

Causes are diverticular disease (about 50 to 70%), colorectal cancer (about 10 to 20%), Crohn disease (about 5 to 10%), radiotherapy, previous pelvic or bowel surgery, appendicitis, foreign body, trauma and infection. Men outnumber women by about 3 to 1 because the uterus lies between bladder and colon.

Pathophysiology. An inflammatory phlegmon or abscess adheres to the bladder dome or posterior wall and erodes through it.

Bowel flora (Escherichia coli, Enterococcus, Klebsiella, anaerobes) pass into the bladder, causing polymicrobial infection. Flow is mainly from bowel to bladder.

Pneumaturia (about 50 to 90%), faecaluria (about 40 to 50%), recurrent or persistent urinary infection, dysuria, haematuria, suprapubic pain and fever. Rectal passage of urine and diarrhoea are uncommon.

History of diverticulitis, change in bowel habit, weight loss, pelvic radiotherapy or Crohn disease points to the cause. Many patients have a palpable pelvic mass.

• CT of the abdomen and pelvis with oral and intravenous contrast is the most sensitive single test, with a reported sensitivity of about 90%. Air in the bladder in a patient not recently catheterised, focal bladder wall thickening next to thickened bowel, and a visible tract support the diagnosis. The tract itself is shown directly in only a proportion.
• Cystoscopy: localised erythema or bullous oedema, usually at the dome or posterior wall, with a visible orifice in a minority. Biopsy the area to exclude malignancy.
• Colonoscopy to exclude carcinoma and to biopsy suspicious bowel.
• MRI for Crohn disease and complex pelvic disease. Urine culture is usually polymicrobial.
• Renal function, full blood count, inflammatory markers and albumin before surgery.

Differential diagnosis.

• Emphysematous cystitis
• Pneumaturia after recent catheterisation or instrumentation
• Vesicovaginal or vesicouterine fistula
• Gas forming urinary infection in diabetes
• Appendiceal or ileal fistula
• Recurrent urinary infection without fistula

• Sepsis: ceftriaxone 2 g intravenously once daily with metronidazole 500 mg intravenously every 8 hours until fever settles, then a culture directed oral agent. Drain abscesses percutaneously under CT control.
• Optimise nutrition, anaemia and steroid exposure before elective surgery.
• Operative treatment: single stage resection of the diseased bowel with primary anastomosis in most patients. Debride the bladder defect and close it in two layers, or leave a tiny defect to heal with catheter drainage. Catheter for 7 to 10 days, with cystography if the repair was complex or the bladder was irradiated.
• Malignancy: en bloc resection with partial cystectomy and full oncological clearance.
• Crohn disease: resect the involved bowel with simple bladder closure, with medical therapy optimised jointly with gastroenterology.
• Defunctioning stoma or a staged procedure for faecal peritonitis, large abscess, immunosuppression, malnutrition or radiation change.
• Laparoscopic resection is feasible in selected patients.
• Non-operative management for frail patients with minimal symptoms or advanced unresectable cancer: culture directed antibiotics for symptomatic episodes, catheter drainage when needed, and diversion for unresectable malignancy.

Monitoring. Urine culture, catheter removal at 7 to 10 days, and review for recurrence (pneumaturia, faecaluria). Cancer follow up is directed by the oncological stage.

Referral and escalation. Joint urology and colorectal referral. Urgent referral for sepsis, peritonitis, abscess or suspected cancer.