c l i n i c a l
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d i s c u s s i o n
Colovesical Fistula
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Colovesical Fistula | ||
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Related narratives: Colovesical Fistula Colovesical fistula usually results from bowel disease, with the bladder being secondarily involved. Half of such fistulas are complications of diverticulitis, secondary to abscess formation between the two organs. The next most common cause of colovesical fistula is malignancy of the colon or female pelvic organs. Although fistula formation is commonly associated with Crohn's disease, it is a much less common disease than the previous two categories, and only 5% of Crohn's patients develop bladder fistulas, and those are usually from the terminal ilium. Prostatectomy, radiotherapy and trauma are less common causes. The condition is more common in men because of the protective interposition of the uterus and vagina in women. Women, particularly after hysterectomy, may develop a colovaginal fistula to the vaginal cuff as a complication of diverticulitis. Diagnosis is often delayed for many months, with dysuria being the most common presenting symptom, and typically a history of recurrent urinary tract infections. Dysuria invariably precedes the pathognomonic pneumaturia and fecaluria. Cystoscopy may demonstrate signs of bullous edema or mucosal inflammation at the site of the fistula, but the fistulous opening is seldom visualized, as in this case. CT scan as well as MRI are the most sensitive diagnostic studies, being able to detect small amounts of air (in the absence of recent instrumentation or active infection) or contrast in the bladder or fistulous tract. Centrifuging the urine for radiologic evidence of barium after a study with rectal contrast (Bourne test) may be a helpful adjunct in confirming the diagnosis. Colonoscopy is valuable to determine the nature of associated bowel disease. Most (75%) colovesical fistulas are amenable to primary resection of the involved bowel and closure of the bladder with or without taking a wedge of bladder. Resection of diverticular disease should be taken down to rectum where the taeneae spread (4 cm above the peritoneal reflection) and where no diverticula are found. Patients with an active inflammatory process may need a period of medical management and/or percutaneous drainage of an abscess to allow the process to resolve, or may require a staged procedure. Ureteral stents are a valuable adjunct because of the anatomic distortion inherent in the inflammatory process or its sequellae. Because of the stricture at 20 cm on colonoscopy, it was not possible to get a biopsy of the involved colon segment, and it was necessary to rule out malignancy that may have altered operative management, so the specimen was opened in the operating room. The absence of mucosal involvement made adenocarcinoma highly unlikely since such lesions start in the mucosa. Prostate cancer may be associated with fistula formation, but more commonly of the rectourethral type. Pelvic radiation associated with prostate cancer in this case, can cause radiation enteritis as well as radiation cystitis. This may have been a contributing factor, but the most likely primary cause remains diverticulitis. References: Greenfield, LJ, (Ed), Surgery, Scientific Principles and Practice, 3rd ed, Lippincott, Williams & Wilkins, Phila, 2001, 824, 1141-2.
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