Fistulas

Abnormal communicating tracts between two internal organs or between an internal organ and the external body surface.

Vesicovaginal and ureterovaginal fistulas usually occur in women who have had a hysterectomy for a benign condition. Patients leak urine continuously or intermittently and have some vulvar excoriation and erythema. Vesicovaginal fistulas occasionally occur many years after radiation therapy for gynecologic cancer; patients typically present with total urinary incontinence. In these cases, recurrent cancer is a strong possibility.

A vesicovaginal fistula can be diagnosed by infusing dye colored with water into the bladder and observing the flow of dye into the vagina, where a tampon had been previously placed. It may also be diagnosed by cystoscopy, pelvic examination, or vaginography; a negative test result does not rule out a fistula. A ureterovaginal fistula is diagnosed by intravenous or retrograde urography.

Fistulas caused by hysterectomy are best treated surgically. Those caused by radiation therapy usually require a diversionary procedure (ie, a urinary conduit).

Urethrovaginal fistulas are very rare but may occur after surgery for stress incontinence or urethral diverticula. Postvoiding incontinence is the usual symptom. Diagnosis is made by endoscopy, urethrography, or both, sometimes using a double-balloon catheter to occlude the internal and external urethral orifices. Many fistulas are missed on the first diagnostic attempt. Treatment involves surgical closure of the fistula and often requires interposition of some vascularized tissue (eg, a labial subcutaneous flap).

Colovesical (enterovesical) fistulas in the elderly may be caused by diverticulitis or, less commonly, by malignant neoplasms. Symptoms include lower abdominal pain, cystitis, pneumaturia (ie, passage of gas in the urine), and hematuria. Colovesical fistulas should be sought promptly in a patient who has recurrent or refractory urinary tract infections, especially when multiple bowel flora are cultured from the urine. Diagnosis is often difficult because the fistulas may intermittently seal, making them difficult to find. Diagnostic methods include barium enema, sigmoidoscopy, cystography, and oral ingestion of charcoal with subsequent examination of the urine for charcoal particles.

The treatment of colovesical fistulas caused by diverticulitis depends on the extent and activity of the diverticulitis. In some cases, the involved segment of sigmoid colon can be resected, with immediate reanastomosis and closure of the opening in the bladder. In other cases, a proximal diverting colostomy is safer than immediate resection, because it allows active diverticulitis to subside before the involved segment of colon is definitively repaired and resected. Fistulas caused by colon cancer usually require excision with proximal diversion and concurrent treatment of the tumor.