Enterourinary Fistula

T.Cristina Sardinha,Samir M.Yebara,and Steven D.Wexner

Enterourinary fistulas are usually the result of underlying pathology involving the gastrointestinal or genitourinary tract. Pathologies such as diverticulitis, Crohn's disease, radiation enteritis, trauma, iatrogenic injury, bladder cancer, appendicitis, colon carcinoma, and gynecologic tumors are causes of enterourinary fistulas. The true incidence of enterourinary fistula is unknown, although the most frequent site of fistulization is between the bowel and the bladder.

Most enterourinary communications involve the bladder and the colon. Although these colovesical fistulas often result from sigmoid diverticulitis (60% of enterovesical fistulas), only 2% of patients with diverticular disease develop colovesical fistula. Malignancy accounts for 20% of enterovesical fistulas. Colorectal adenocarcinoma may adhere and directly invade the bladder, leading to fistuliza-tion in 0.6% of patients.1,2 Moreover, cancer of the cervix, prostate, ovary, and lymphoma can also occasionally result in enterourinary fistulas. However, primary bladder cancer has rarely been found to fistulize to the bowel, perhaps as a result of its relatively early detection.

Colovesical fistulas are more common in men, probably because of the male anatomy maintaining close proximity between the sigmoid colon and the bladder. This is contrary to the female anatomy, where the uterus forms a barrier between the bladder and the sigmoid colon, except in posthysterectomy patients. Colovesical fistulas are not a usual complication of diverticulitis,because most fistulas are at the dome of the bladder. Colovesical fistulas often present with symptoms of bladder irritability,dysuria,pneumaturia, fecaluria, and recurrent urinary tract infections.3 In addition to clinical signs and symptoms of an abnormal colovesical communication, complementary tests may be required to confirm the diagnosis (Table 13-3.1). Computerized tomography findings include air in the bladder, focal bladder wall and adjacent bowel wall thickening, and surrounding inflammation. A water-soluble enema may also identify the fistulous tract in addition to diverticular disease or tumor. Moreover, a colonoscopy with biopsies should be performed to exclude invasive carcinoma. Cystography is more accurate than intravenous pyelography, and if bladder cancer is suspected, a cystoscopy with biopsies should also be performed. However, cystoscopy rarely reveals the fistula; common findings include bullous edema and erythema typically at the dome of the bladder.

Diverticulitis represents 65% of enterovesical fistulae.4 Diverticular fistulae are almost entirely colovesical. The principal cause of a fistula in diverticular disease is a peri-colic abscess. The abscess is walled off by omentum and small bowel and penetrates the dome of the bladder, and may eventually produce perforation into the bladder, causing a fistula.4

Crohn's disease accounts for approximately 10% of vesi-coenteric fistulae and is the most frequent cause of an ileovesical fistula because of the anatomic proximity of the ileum to the dome of the bladder.5 Pneumaturia in a patient with Crohn's disease is a strong indicator of the presence of an enterovesical fistula.6 The transmural nature of the inflammation characteristic of Crohn's colitis often results in adherence to other organs. Consequent erosion into adjacent organs can then give rise to a fistula. The mean duration of Crohn's disease at the time of first symptom of fistula formation is 10 years, and the average patient age is 30 years.

The treatment of colovesical fistulae involves colon resection and drainage of the bladder with a Foley catheter. Typically, a laparoscopic sigmoid colectomy is the ideal option. Primary repair of the bladder opening is only necessary when easily identified with relatively healthy surrounding tissues. In the former case, a few sutures can be placed, whereas in the latter, a resection of the inflamed area may be necessary. The operation should be performed electively after adequate bowel preparation. Emergency surgery is frequently unjustified, because a colostomy will likely be required in this situation. In case the patient presents with urinary sepsis, this should be controlled with adequate broad-spectrum antibiotics and fluid resuscitation before surgery.

Nonoperative therapy of colovesical fistula with prolonged antibiotic therapy has been reported as a therapeu-

Table 13-3.1. Clinical features and diagnostic tools.2,3

Signs and Symptoms

Diagnostic Investigations

Cystitis

Cystoscopy

Pneumaturia

Contrast enema

Fecaluria

Computed tomography scan

Hematuria

Oral contrast: 1. barium,2. charcoal, 3. methylene blue (followed the next day by a centrifuged urine sample)

Fever

Abdominal tenderness

Cystography

tic option in high-risk diverticulitis patients. However, fecal diversion is often required for recurrent urinary tract infections. Nonetheless, some patients will present complete healing of the fistulous tract, and requirement for resection will depend on the nature of the colonic pathology. Iatrogenic enterourinary fistulas are often a consequence of surgical procedures such as prostatectomies, resection of rectal lesions, hysterectomy, laparoscopic inguinal hernia repair, and other pelvic operations. Radiation therapy for gynecologic or urologic malignancies may lead to progressive bowel injury culminating with perforation and often fistulization. A common example is the development of rectourethral fistula postradiation therapy of prostate cancer. This complex problem presents as ure-thral elimination of gas and stool as well as recurrent urinary sepsis. Diagnostic modalities include retrograde urethrogram and proctoscopy. The rectum is often inflamed and the mucosa friable with easy bleeding. This problem is more evident in the anterior rectal wall directly under the prostate or prostatectomy site. Fecal diversion and/or urinary diversion alone do not completely eliminate recurrent urinary infections or healing of the rectourethral fistula. Moreover, patients prefer to avoid permanent stomas. The use of rectal advancement flaps has been reported, but the success rate of this approach is unclear.7 We advocate local procedures with interposition of healthy muscle flap. As well we prefer to use the gracilis muscle because of its low morbidity and easy harvesting (see Chapter 13-2, Figure 13-2.6). We have successfully performed the gracilis muscle transposition with very gratifying results in more than 30 patients with rectourethral fistula posttreatment of prostate cancer. Temporary fecal diversion and suprapubic cystostomy are also performed either at the time of or before muscle harvest and transposition. Reversal of the fecal diversion and removal of the cystostomy tube was performed after documentation of complete fistula healing.

Enterourinary fistula involving the small bowel and bladder is often diagnosed with a small bowel series or computerized tomography and frequently treated with segmental small bowel resection. The bladder can be primarily repaired and drained with a bladder catheter or just drained if the bladder opening is not clearly identified. In both instances, a follow-up cystogram should be performed approximately 6 weeks after the operation, before removal of the bladder catheter. The surgical treatment of radiation-induced fistula can be challenging, and a diverting proximal colostomy or ileostomy is advisable. Moreover, enterourinary fistulas in patients with Crohn's disease may respond to medical management.5 Therefore, drugs such as tumor necrosis factor inhibitors should be considered in patients without evidence of significant infection. However, these agents may only delay the need for surgery by transient healing. The transmural inflammatory process that occurs in the bowel is not seen in the bladder, which allows for safe primary closure with absorbable suture.

In summary, enterourinary fistulas often require a mul-tidisciplinary approach. We advocate elective laparoscopic surgery to treat most fistulas involving the small bowel or colon and the bladder. Nonetheless, all patients should be consented for and advised of the possibility of a laparo-tomy. Fecal diversion must be kept in mind, particularly in patients with significant radiation enteritis. However, rec-tourethral fistulas are better managed with local procedures, with our preference being the gracilis interposition.

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