Vesicoenteric Fistula

January 11, 2009

Although rare in daily clinical practice, the diagnosis of an acquired communication or fistula between the urinary tract and the intestines is always a challenge to the ingenuity and clinical acumen of the urologist and, later, to the good surgical judgment as to whether surgery is indicated or not, and whether to do it in a single or in several stages. Most manifestations of the condition occur toward the urinary tract, with passage of fecal matter and flatus from the gut to the bladder rather than in the opposite direction, directing these patients toward a urologist who will initiate the proper workup and participate actively in the surgical care.

Vesicoenteric fistulas are usually the consequence of inflammatory processes of the bowel, mainly diverticulitis; colorectal cancer and, more rarely, carcinoma of the bladder; trauma; and iatrogenic fistulas between bladder and sigmoid colon as a result of prostatic surgery, either endoscopic or open.

Diverticulitis has long been identified as the most common cause of vesicoenteric fistula, ranging in incidence from 36% to 85%, with an average of 50%, with colonic malignancy, granulomatous bowel disease, and radiation therapy accounting for the majority of the remainder in a large series.1,5 Before 1950, one in 3,000 surgical hospitalizations and 23% of patients who required surgery for diverticulitis had vesicoenteric fistulas reflecting late diagnosis and treatment.3 Diverticulosis occurs in at least half of patients older than 60 years old. Inflammation of these mucosal outpouches occurs 1.5 to 3.0 times more frequently in men than in women, whereas vesicocolonic fistula is up to five times as often in men as in women, indicating that the uterus may play a role in the prevention of fistulization to the bladder. Moreover, in women with diverticulitis, vaginocolonic fistulas are much more frequent than vesicolonic fistulas, 7.5:1.0, further supporting the role of the uterus as a protective anatomic barrier.

Colorectal adenocarcinoma is the cause of fistula in 10% to 16% of cases, being the second most frequent entity after diverticulitis. Half of these neoplastic fistulas are vesicosigmoideal. Other pelvic neoplasias, such as bladder and cervical carcinoma, are less frequent causes of fistula, ranging in incidence between 5% and 10% each. Enterovesical fistula is a rare complication of pelvic radiotherapy for gynecologic cancer, with recurrent neoplasia being the most common cause of fistulization, though some patients without recurrence will develop a fistula. High-risk factors for radiation morbidity include previous surgery, pelvic inflammatory disease, adjuvant hyperbaric oxygen, or locally high doses of radiotherapy caused by suboptimal geometry and technique. The range of radiation morbidity is variable, some patients had small fistulas, others had extensive fistulization and radionecrosis. The site of the radiation-induced fistula varies: colovesical fistulas, enterovesical fistulas, and some patients with fistulas involving both the small and large bowel. Rarely, the cause of the vesicoenteric fistula is transitional-cell carcinoma of the bladder.

Inflammatory bowel disease accounts for approximately 3.5% of cases of vesicoenteric fistulas, with Crohn’s disease being the most common cause. Generally, patients with Crohn’s disease were an average of 20 years younger than the patient with cancer or diverticulitis. Crohn’s disease is more likely to produce multiple fistulas: ileovesical, ileoascending colonic, and ileosigmoidal. Other less common inflammatory processes associated with vesicoenteric fistulas include appendiceal abscess, tuberculosis, and actinomycosis.

DIAGNOSIS

Clinical Manifestations

Despite the fact that most vesicoenteric fistulas are the result of primary bowel disease, patients most often have urologic symptoms, with a significant absence of localizing intestinal symptoms in up to half of patients. A wide range of symptoms exist that are of variable intensity but generally of insidious nature, making the diagnosis of a fistula elusive and delayed.

Gastrointestinal symptoms of vesicoenteric fistulas include abdominal pain, diarrhea, constipation, intestinal obstruction, and acute abdomen, which are manifestations of the underlying pathology. Urologic symptoms may be lower tract such as bladder irritation, frequency, urgency, dysuria, and hematuria; those related to recurrent urinary tract infections; and upper tract with accompanying systemic symptoms, fever, and chills.

The most relevant and pathognomonic manifestations, pneumaturia and fecaluria, passage of gas and feces, respectively, per urethra, occur in 40% to 83% of patients and immediately point toward the diagnosis. However, their absence does not rule out the entity; moreover, even if present, these symptoms may be overlooked or not recognized if the patient is not directly questioned or instructed to search for them carefully. Pneumaturia occurs twice as commonly as fecaluria because the passage of solid particles through the fistula is difficult. Interestingly, passage of urine per rectum is rare because of the higher colonic pressure and occurs only after a diverting colostomy or in association with severe bladder outlet obstruction. Bladder irritative symptoms associated with known diverticulosis and bouts of diverticulitis or Crohn’s disease should arouse suspicion of a prodromic stage of a vesicoenteric fistula.

Positive physical findings are few. An abdominal mass is felt in a third of patients, and abdominal tenderness and guarding, indicating local peritonitis, is seen in one-third to half of the patients. Rarely, one can find a cutaneous fistula and acute scrotum secondary to urinary tract infection. Urinalysis may show striated muscle fibers (rhabdomyocytes) derived from undigested meat residue from stool, in addition to the usual findings of urinary infection. Urine cultures generally grow a single species, predominantly Escherichia coli, instead of the falsely expected mixed growth. Temporary closure of the fistula by edema may render a urine culture negative in 5% to 10% of patients.

Preoperative Assessment

Once the diagnosis of vesicoenteric fistula is entertained, it is important to document both the presence and site of the fistula. Although it is more frequently found between the sigmoid colon and bladder, other locations (ileal, appendicular, colic, rectal, and Meckel’s diverticulum) must be ruled out. Additionally, any involvement of adjacent viscera needs to be identified.

Enterovesical fistula is a challenging entity, the etiology of which may be suspected from the patient’s history or physical assessment. The definite diagnosis of enterovesical fistula can remain difficult despite the many methods of diagnosis, including functional, imaging, and endoscopic studies.

Functional Studies

Activated charcoal, nonabsorbable through intestinal mucosa, administered orally or through the defunctionalized end of a colostomy, produces charcoaluria. This method is easy, inexpensive, noninvasive, and yields the highest rate of positive results.

Visible dyes (phenazopyridine, methylene blue, indigo carmine, Congo red) administered through enemas in undiverted patients or through urethral or suprapubic catheter, searching for stained stools.

Search for pneumaturia with the patient voiding in a water-filled tub.

Oral nonabsorbable radioisotope, e.g., 51Cr-labeled sodium chromate, producing quantitated radioactivity in urine over 2 to 3 days.

Imaging Studies

Intravenous pyelogram is generally of little help. Rarely, one sees dye in the colon; more frequently, some nonspecific abnormalities related to the primary process or associated inflammatory process, gas in urinary tract, bladder wall irregularities, ureteral strictures, or hydronephrosis.

Retrograde and voiding cystogram—twice as successful as an intravenous pyelogram in diagnosing this condition, 35% to 44%—and one of the mandatory methods of evaluation.

Retrograde pyelogram, used only if there is any suspicion of ureteral involvement in the process.

Barium enema is unequivocally positive in only 20% to 42% of cases. However, it remains a very important study to delineate the process that is producing the fistula. Postevacuation films may enhance the sensitivity of the study. Also, the patient can be instructed to collect the voided urine in a plastic or glass container over a few hours in an attempt to see the barium directly or by means of a radiograph of the container. A more refined version of this concept is the Bourne test, in which a drop of sediment of centrifuged urine is placed on an x-ray cassette and compared radiologically with a control urine sample.

Abdominal ultrasound has been used to diagnose complications of Crohn’s disease such as bowel loop wall thickening, abscess, lymph node enlargement, and vesicoenteric fistulas. Abdominal ultrasound has been found to yield the first diagnostic information on inflammatory bowel with a high correlation to surgical findings. Also, it can differentiate pelvic complications of these intestinal conditions.

Upper gastrointestinal (UGI) series rarely are indicated unless the colon workup is normal or there is a suspicion of a complex fistula involving the ileum.

Computed tomographic scan (CT) of abdomen and pelvis is a very useful study, with the following positive findings in the cases examined: air within the bladder in 83%, thickening of the intestine and bladder wall at the site of the fistula in 100%, and paravesical mass in 87%. This justifies it as a preliminary step in any suspected case of vesicoenteric fistula.9 A CT finding consistent with the diagnosis of appendicovesical fistula is calcification of a thickened bladder wall adjacent to the cecum on noncontrast CT, which is a fecalith in the lumen of the fistula. A CT scan of the abdomen and pelvis is, therefore, recommended in the evaluation of the majority of patients with suspected enterovesical fistulas.

Magnetic resonance imaging (MRI) has been used in patients with Crohn’s disease to evaluate cutaneous, deep perineal, or enterovesical fistulas or abscesses, with good correlation with clinical examination under anesthesia. It is more likely that a negative MRI correlates better with other ancillary methods.

Endoscopic Studies

Cystoscopy is, by far, the most valuable study to diagnose and localize the fistula, with a success rate of 32% to 87%. Nine of ten cystoscopies show mucosal abnormalities, feces, particulate matter, barium, and the so-called Pugh’s villous reaction, papillomatous epithelial growth, which sometimes can be misdiagnosed as low-grade transitional cell carcinoma. The fistula or suspicious area usually is located in the high left posterolateral wall when the primary cause is diverticulitis or cancer (colonic, vesical, or uterine). The fistula is usually located in the right or anterior wall in cases of Crohn’s disease or lesions of the cecum or appendix. It sometimes is possible to catheterize the suspect tract and obtain radiographic studies. Likewise, whether or not an obvious fistulous opening is visualized, a biopsy specimen can be taken from the suspect area to rule out an urothelial, gynecologic, or intestinal malignancy. From 10% to 20% of patients with vesicoenteric fistulas have completely normal endoscopic results.

Endoscopic procedures of the lower gastrointestinal tract, colonoscopy or proctosigmoidoscopy, are of limited help. Perhaps the insufflation of air during these procedures may help uncover pneumaturia. These studies are indicated to evaluate the large bowel, to assess the magnitude of the primary problem (diverticula, neoplasia) and its sequelae (obstruction, mass) and to plan an optimal operation. Also, even if the fistula is the result of inflammatory bowel disease, there can be a concurrent bowel neoplasm in 3% to 14% of cases.

In summary, cystoscopy (60%) and cystography (44%) seem to be the most sensitive diagnostic studies. Computerized axial tomography scanning, cystoscopy, charcoaluria, and barium enema are useful in making the diagnosis. The IVP and colonoscopy are generally not useful procedures for the diagnosis of VE fistulas.6 Other imaging techniques, though less effective for diagnosis, were useful in assessing the status of the GI tract and, sometimes, determining the etiology of the fistula.

INDICATIONS FOR SURGERY

Surgical therapy aimed toward resolution of the primary process and abnormal communication is required and feasible in most cases. Ideally, the surgeon should consider a primary resection in properly selected patients, without risking the repair or the life of the patient. All possible etiologies can be treated this way. A selection of criteria regarding patient selection and characteristics of the fistula and the bowel anastomosis must be met for primary (one-stage) resection to be successful .

ALTERNATIVE THERAPY

On occasions, especially when the vesicoenteric fistula does not meet all above-mentioned criteria, it may be wise to treat preliminarily with a diverting colostomy in order to control the inflammatory process and avoid the continuance of infection and sepsis. Generally, this is done alone, and future procedures are planned. Traditionally, when a diverting colostomy has been done as a first stage, a second operation resolves the primary bowel process and the fistula proper (bowel resection plus partial cystectomy), and the colostomy is preserved rather than closed to protect the intestinal anastomosis. The closure of the colostomy can be done 4 to 6 weeks later as a third stage, to take full advantage of it. Although it is safe, at present this extended multistaged approach does not seem cost-efficient. Ideally, once the diverted patient is fully recovered of the acute event, one can proceed with excision of the fistula and reconstruction, with closure of the colostomy in the same session if local conditions allow it, in order to avoid a third operation.

During a single-stage operation, an unexpected intraoperative finding may induce a change of plans and convert a one-stage procedure to a multistaged operation. In this case, the main problem, the fistula, is excised, bowel and bladder reconstruction is accomplished, and then the anastomosis is protected by a colostomy, which will be closed as a second stage. All these alternatives should be fully discussed with the patient.

In debilitated patients with reasonable and comfortable life expectancies, a palliative colostomy may be the only procedure considered. In extremely debilitated patients, especially if there is unresectable or metastatic neoplasia, an expectant and supportive medical management (intermittent antibacterial treatment) may be all that is indicated. In one series one-tenth of the patients were not candidates for operation, and one-fourth of the patients did not undergo complete operative resolution and restoration of enteric and urinary continuity.

SURGICAL TECHNIQUE

Regardless of the site of the vesicoenteric fistula, the bowel needs to be prepared mechanically and bacteriologically. The patient is started in a low-roughage diet several days before entering the hospital, and cathartics and enemas are administered the day before surgery. Nonabsorbable oral antibiotics are given starting 24 hours for prophylaxis against both gram-negative and anaerobic bowel flora. It is advisable to initiate a program of parenteral hydration and antibiotic prophylaxis several hours before surgery, using drugs that cover gram-negative bacteria and, in the case of a colon fistula, anaerobics. If the patient is severely malnourished, oral or parenteral hyperalimentation can be started days to weeks before surgery and maintained through the postoperative period.

Surgery is started by a midline or paramedian incision in all cases, regardless of whether a prior fecal diversion has been done, to allow a transperitoneal approach with careful assessment of the inflammatory mass and intervening viscera as well as the remainder of the bowel and other intra-abdominal organs. This incision affords cephalad extension if needed. The abdomen is entered, and all adhesions are lysed; small bowel contents are removed from the pelvis. The area of the fistula is identified, and the intestine is sharply dissected from its attachment to the bladder. In patients with Crohn’s disease, the indication for surgery was the fistula alone in a third of the cases and the fistula plus another complication of the disease in two-thirds of the patients.8 These include enteroenteral, ileogenital, and enterocutaneous fistulas and intra-abdominal abscesses. The surgical team must be prepared for this eventuality. If the patient has not been diverted previously, the surgeon must decide either to proceed with a primary reconstruction without colostomy or, if the conditions are less than ideal, to protect the anastomosis with a colostomy. In case of a previous colostomy, one either takes advantage of the colostomy and plans to close it several weeks after the reconstruction or closes it immediately as mentioned.

Surgical treatment of a vesicoenteric fistula ideally consists of the excision of the diseased bowel, partial resection of the involved bladder, and interposition of a vascularized tissue between the two viscera. Urinary diversion is ordinarily attained with a urethral catheter. The use of a suprapubic catheter is optional and depends on the confidence of the surgeon in the vesical repair, local and urethral conditions, and presumed duration of urinary leakage. In case of ureteric involvement, stenting or ureteroureterostomy may be required. Bowel anastomosis is done in the standard one- or two-layer fashion or with a bowel stapler.

After both systems are reconstructed, it is advisable to fill the potential dead space between them with a vascularized tissue to support the repair and improve tissue healing, which is impaired by inflammation and infection. An omental flap is ideal to accomplish this task, either by simply fixing it between bladder and bowel with tacking sutures if the omentum is long or by creating a pedicle flap based in the right gastroepiploic artery, separating the left gastric attachments. Also, one may interpose flaps of peritoneum, muscle, or fibroadipose tissue in less serious cases. Gold foil and lyophilized human dura have been used in some cases. Colovesical fistulas associated with diverticulitis can be treated laparoscopically in a one-stage repair. It has been suggested that this operation is safe, has minimal pain, absent ileus, and a short postoperative stay.

Inflammatory bowel disease, especially Crohn’s disease, may produce filiform tracts, which can make the fistula localization difficult. Moreover, these patients are subject to more recurrences. Therefore, although simple separation of bowel and bladder with bowel resection and oversewing of the bladder wall may suffice, it may be better to proceed with a limited partial cystectomy. The involved bladder is resected to allow a two- or three-layer closure with absorbable sutures, bringing together edges of fresh, noninflamed tissue. If the defect seems too large, one may resort to rotated bladder flaps or rearrangements of bladder tissue as the ventrodorsal repair, wherein a longitudinal cystotomy is closed in a transverse manner. Rarely, a small bowel graft may be necessary to cover an unusually large defect, and in some cases, the cystotomy has been left open, and a urethral catheter left in place for at least 1 week with healing and no late recurrences.

Repair of Rectovesical Fistula (York-Mason Procedure)

A special situation may arise when the fistula involves the bladder and rectum instead of the sigmoid colon, as observed after injuries sustained during prostatic surgery and pelvic fractures. Repair of these fistulas using a posterior sagittal, transanal, transrectal (modified York–Mason) approach has been advocated with excellent results. This repair is possible without colostomy in a patient who has undergone a complete mechanical and bacteriologic bowel prep. Before surgery, a combined cystoscopy and rectal examination are performed to localize the fistula and establish all anatomic relationships with the ureteral orifices, urinary sphincter, and anorectal anatomy. One can insert a catheter or guide wire through the fistula to facilitate dissection.

The patient is placed in the prone jackknife position, with buttocks spread apart. An incision is made from the anal verge to the sacrococcygeal articulation, dividing all muscular bundles of the posterior anus and the entire thickness of the posterior rectal wall and tagging them with sutures for accurate reconstruction at the end of the procedure. Once the fistula is located, it is excised down to its junction with the bladder or prostate, removing all inflammatory tissues to optimize the closure of both defects. Both organs are closed in two layers of absorbable sutures. The first rectal wall layer involves muscle and submucosa, and the second, rectal mucosa in an everting fashion. Sometimes a demucosalized rectal flap can be used to buttress this repair. Then, the dorsal rectal and anal mucosa are closed with a chromic running suture. Careful approximation of the dentate and pectinate lines is desirable. The anal sphincter is reconstructed with the previously placed tagged opposing sutures tied together. Drains are removed on the fifth postoperative day; however, discharge can be accomplished on the second postoperative day. Vesical drainage is effected with a Foley catheter as in any vesical reconstruction.

This approach is simple, rapid, and performed through fresh tissues uninvolved in the inflammatory process and is a significant improvement over the transabdominal, transvesical, or transperineal approaches, where the depth of these pelvic organs makes these procedures difficult and lengthy. Postoperative pain is minimal, and no instances of fecal incontinence or anal strictures were reported in this series.

OUTCOMES

Complications

Any intervention involving an intestinal anastomosis needs to be protected by nasogastric suction for several days until the ileus resolves, generally in 3 to 5 days, heralded by the passage of flatus or by a bowel movement. Complications include bowel anastomotic leaks with resultant peritonitis, external fecal fistula or pelvic abscess, prolonged ileus, or bowel obstruction. In the event of any of these complications, surgery may again be indicated, perhaps in the form of fecal diversion, and appropriate drainage or repeat reconstruction may be necessary.

Results

When the vesicoenteric fistula is caused by inflammatory disease (diverticulitis, Crohn’s disease, etc.), it is likely that a one-stage bowel resection and closure of the fistula can be done (66%). In patients with a colonic malignancy, pelvic abscess, or with postradiation changes, it is more prudent to close the fistula in stages with fecal diversion and later closure. Comparisons between groups of patients treated with a single-stage versus two-stage repair showed lower morbidity in the patients who underwent one-stage repair, concluding that single-stage repair can be achieved with low morbidity and mortality in many candidates.6 In another series, there was no statistical difference in the complication rate between groups treated with single- and multistage repair. The recurrence rate of vesicoenteric fistula following surgical repair is up to 6.5% of patients, especially if the fistula is the result of inflammatory bowel disease other than diverticulitis (Crohn’s disease) or of pelvic neoplasia (prostate, colon, or endometrium). Surgical procedures that resect necrotic fistulized bowel and result in complete separation of the gastrointestinal and genitourinary tracts provided the best results in patients with radiation-induced enterovesical fistulas.