Normally, the urinary system is completely separated from the alimentary canal. Connections can occur as a result of (1) incomplete separation of the 2 systems during embryonic development (eg, failure of the urorectal septum to divide the common cloaca), (2) infection, (3) inflammatory conditions, (4) cancer, (5) injury, or (6) iatrogenically as a result of surgical misadventures or postoperative complications. In the general practice of medicine, the most common misconnection of the 2 systems occurs as a result of bowel disease that occurs adjacent to and erupts into the bladder. While fistulae can also occur from the bowel to the ureter and the renal pelvis, these occurrences are uncommon in the absence of trauma or surgical interventions. This article focuses on the more common causes, presentations, and treatments of enterovesical fistulae.
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History of the Procedure: As early as the second century AD, Rufus of Ephesus described fistulae between the bowel and the bladder. The common causes of acquired vesicoenteric fistulae have shifted from diseases of the past (eg, typhoid, amebiasis, syphilis, tuberculosis) to diverticulitis, malignancy, Crohn disease, and iatrogenic causes. Treatments have also evolved. In 1888, some suggested that colovesical fistulae "might be cured by a course of Bristol water and ass's milk." Although more invasive, certainly less colorful, and possibly more palatable, a single-stage surgical approach is more commonly employed today.
Problem: A fistula is an abnormal communication between 2 epithelialized surfaces. Vesicoenteric fistulae, also known as enterovesical or intestinovesical fistulae, occur between the bowel and the bladder. Vesicoenteric fistulae can be divided into 4 primary categories based on the bowel segment involved, as follows: (1) colovesical, (2) rectovesical (including recto-urethral), (3) ileovesical, and (4) appendicovesical fistulae. A colovesical fistula is the most common form of vesicointestinal fistula and is most commonly located between the sigmoid colon and the dome of the bladder. Rectourethral and rectovesical fistulae are observed in the postoperative setting, such as after prostatectomy, as a consequence of chronic infection or tissue destruction accompanying massive decubiti, or in the setting of acute infections such as Fournier gangrene.
Frequency: Colovesical fistulae are the most common type of fistulous communication between the urinary bladder and the bowel. The relative frequency of colovesical fistulae is difficult to ascertain because multiple disease processes and surgical procedures could be complicated by such fistulae.
The incidence of fistulae in patients with diverticular disease, the most common cause of colovesical fistula, is generally accepted to be 2%, although referral centers have reported higher percentages. Only 0.6% of carcinomas of the colon lead to fistula formation.
Colovesical fistulae occur more commonly in males, with a male-to-female ratio of 3:1. The lower incidence in females is thought to be due to interposition of the uterus and adnexa between the bladder and the colon. A 50% previous hysterectomy rate was found among women with colovesical fistulae. Other types of fistulae (typically iatrogenic such as enterovaginal, ureterovaginal, and vesicovaginal) occur more commonly than colovesical fistulae in women.
Etiology: Fistula formation is believed to evolve from a localized perforation that has an adherent adjacent viscus. The pathologic process is almost always intestinal. Pathologic processes characteristic of particular intestinal segments cause those segments to adhere to the bladder. Therefore, the location of the segment can suggest intestinal pathology.
Colovesical fistulae primarily result from diverticular disease. Ileovesical fistulae are most likely associated with Crohn disease. Rectovesical fistulae occur more frequently in the setting of trauma or malignancy. Appendicovesical fistulae tend to be associated with a history of appendicitis.
Pathophysiology: Fistulae may be either congenital or acquired (eg, inflammatory, surgical, neoplastic). Congenital vesicoenteric fistulae are rare and are often associated with an imperforate anus.
Diverticulitis accounts for approximately 50-70% of vesicoenteric fistulae. Diverticular fistulae are almost entirely colovesical. Diverticulitis complicated by a phlegmon or an abscess may adhere to the bladder and may eventually produce perforation into the bladder, causing a fistula. This complication occurs in 2-4% of cases of diverticulitis, although referral centers have reported a higher incidence.
Crohn disease accounts for approximately 10% of vesicoenteric fistulae and is the most frequent cause of an ileovesical fistula. Ileovesical fistulae develop in 10% of patients with regional ileitis. The transmural nature of the inflammation characteristic of Crohn colitis often results in adherence to other organs. Subsequent erosion into adjacent organs can then give rise to a fistula. The mean duration of Crohn disease at the time of first symptoms of fistula formation is 10 years, and the average patient age is 30 years.
Less common inflammatory causes of colovesical fistulae include Meckel diverticulum, genitourinary coccidioidomycosis, and pelvic actinomycosis. Appendicovesical fistulae may complicate appendicitis. Enterovesical formation from lymphadenopathy associated with Fabry disease has been reported. Rarely, the bladder can be the origin of the inflammatory process, as noted in a case report from Spain of bladder gangrene that caused a colovesical fistula in a patient with diabetes mellitus.
Malignancy accounts for approximately 20% of vesicoenteric fistulae. Colorectal cancer is the most common malignancy associated with a vesicoenteric fistula. Malignancy is the second most common cause of colovesical fistulae.
Transmural carcinomas of the colon and rectum may adhere to adjacent organs and may eventually invade directly, causing development of a fistula. Such an event is uncommon today because most carcinomas are diagnosed and treated before this advanced stage develops.
Occasionally, carcinomas of the bladder, cervix, prostate, and ovary are implicated, and incidents involving small bowel lymphoma have been reported. Rectovesical fistulae are frequently associated with malignancy. Interestingly, bladder carcinoma rarely, if ever, is associated with fistula formation. The reason for this may be earlier detection of bladder cancer.
Iatrogenic and/or traumatic pathophysiology
Iatrogenic fistulae are usually induced by surgical procedures, possibly tissue radiation, cancer, and/or infection. Surgical procedures, including prostatectomies, resections of benign or malignant rectal lesions, and laparoscopic inguinal hernia repair, are well-documented causes of rectovesical and rectourethral fistulae. Unrecognized rectal injury at the time of radical prostatectomy is an uncommon but well-documented etiology of rectourethral fistula.
External beam radiation or brachytherapy may cause bowel injury. Radiation-associated fistulae usually develop years after radiation therapy for a gynecologic or urologic malignancy. Fistulae develop spontaneously after perforation of the irradiated intestine, with the development of an abscess in the pelvis that subsequently drains into the adjacent bladder. Radiation-associated fistulae usually are complex and often involve more than one organ (eg, colon to bladder). Fistulae as a result of cytotoxic therapy have been reported in a patient undergoing a CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) regimen for non-Hodgkin lymphoma.
Urethral disruption from blunt abdominal trauma or a penetrating injury can result in fistulae, but the fistulae typically are urethrorectal in nature. Foreign bodies in the bowel (eg, swallowed chicken bones or toothpicks) and peritoneum (eg, lost gallstone during laparoscopic cholecystectomy) have been reported to cause colovesical fistulae.
Clinical: The presenting symptoms and signs of enterovesical fistulae occur primarily in the urinary tract. Symptoms include suprapubic pain, irritative voiding symptoms, and symptoms associated with chronic urinary tract infection (UTI). Signs include abnormal urinalysis findings, malodorous urine, debris in the urine, hematuria, and UTIs.
The hallmark of enterovesicular fistulae may be described as Gouverneur syndrome, namely, suprapubic pain, frequency, dysuria, and tenesmus. Chills and fever are less common, and a colovesical fistula manifesting as sepsis is uncommon. Sepsis has been reported in 70% of patients with urinary outlet obstruction. The fistula may be asymptomatic and is seldom accompanied by dramatic or sudden abdominal symptoms or diarrhea. In most series, patients have been treated for recurrent UTI for 4-12 months before a diagnosis of fistula is made.
Pneumaturia and fecaluria may be intermittent and must be carefully sought in the history. Pneumaturia occurs in approximately 60% of patients but is nonspecific because it can be caused by gas-producing organisms (eg, Clostridium, yeast) in the bladder, particularly in patients with diabetes mellitus (ie, fermentation of diabetic urine) or in those undergoing urinary tract instrumentation. Pneumaturia is more likely to occur in patients with diverticulitis or Crohn disease than in those with cancer. Fecaluria is pathognomonic of a fistula and occurs in approximately 40% of cases. The flow through the fistula predominantly occurs from the bowel to the bladder. Patients very rarely may pass urine from the rectum.
Symptoms of the underlying disease causing the fistula may be present. Abdominal pain is a more frequent occurrence in patients with Crohn disease, but an abdominal mass is observed in fewer than 30% of patients. In patients with Crohn disease who have a fistula, abdominal mass and abscess occur more frequently.
The documented presence of a fistula that is causing symptoms or adversely affecting quality of life is an indication for surgical intervention in patients with enterovesical fistulae. Fistulae should be repaired in patients with abdominal pain, dysuria, malodorous urine, incontinence, urinary outlet obstruction, recurrent UTIs, bouts of sepsis, and pyelonephritis. Patients who are poor operative risks may be treated with medical therapy but may ultimately require at least diverting surgery if symptoms persist. Patients with terminal cancer often are better treated conservatively or with simple diversions.
Relevant Anatomy: Fistula formation is believed to evolve from a localized perforation to which an adjacent viscus adheres. The pathologic process almost always is intestinal and characteristic to particular intestinal segments that adhere to the bladder. The segments that can most commonly be found in proximity to the bladder are the rectum, sigmoid colon, ileum, jejunum, and appendix. Furthermore, the segment of bowel that is involved can suggest the intestinal pathology.
Colovesical fistulae primarily result from sigmoid diverticular disease. Ileovesical fistulae are most likely associated with Crohn disease. Rectovesical fistulae occur more frequently in trauma, surgery, or malignancy. Appendicovesical fistulae tend to be associated with a history of appendicitis.
Contraindications: Poor overall general health, inability to tolerate general or regional anesthesia, and terminal cancer are contraindications for aggressive management to cure a fistula. Patients with these contraindications may be served better with medical therapy or less invasive diversions (eg, colostomy, ureterostomy, percutaneous drainage).
Staging: Staging is appropriate when the etiology of the fistula is carcinoma. The staging of colorectal carcinoma is discussed in other eMedicine articles such as Colon, Adenocarcinoma, Rectal Carcinoma, and Colon Cancer, Adenocarcinoma.
Medical therapy: Nonsurgical treatment of colovesical fistulae may be a viable option in select patients who can be maintained on antibacterial therapy for symptomatic relief for a prolonged period.
Conservative treatment of colovesical fistulae has been performed in patients with diverticulitis who are deemed to be a surgical risk. In highly select patients, nonoperative therapy has been reported as a viable treatment option. Six patients observed for 3-14 years encountered little inconvenience and were without significant complications while on intermittent antibacterial therapy alone. Recent interest in conservative management has led to animal experiments showing that colovesical fistulae can be well tolerated in the absence of distal urinary or bowel obstruction (which could lead to sepsis). If a fistula closes spontaneously, which occurs in as many as 50% of patients with diverticulitis, requirements for resection depend on the nature of the underlying colonic disease. Some patients tolerate a colovesical fistula so well that surgery is deferred indefinitely.
Enterovesical fistulae due to Crohn disease may be managed conservatively with sulfasalazine, corticosteroids, antibiotics (eg, metronidazole), and 6-mercaptopurine. Six patients continued with medical therapy alone after a mean of 5 years with no instances of pyelonephritis. Two patients had successful control of their urinary symptoms. Eleven patients eventually underwent bowel resection, but persistence of the enterovesical fistula was the primary indication for elective surgery in only 2 patients.
Patients with advanced carcinoma may be treated with catheter drainage of the bladder alone or supravesical percutaneous diversion.
Colovesical fistulae can almost always be treated with resection of the involved segment of colon and primary reanastomosis. When the etiology of the fistula is inflammation, the general principle is resection of the primarily affected diseased segment of intestine with or without closure of the defect in the bladder. Healing of the bladder usually is uneventful and is allowed to occur with temporary urethral catheter drainage. Suprapubic tube diversion is an option but is not necessary in this author's experience.
Staged repairs may be more judicious in patients with large intervening pelvic abscesses or in those with advanced malignancy or radiation changes. Most cases do not involve abscesses. If an abscess is present, spontaneous drainage through the fistula into the bladder may alleviate the immediate need for drainage if adequate bladder emptying under low pressure is occurring. Further operations may be delayed pending culture results and after adequate antibiotic therapy has reduced the inflammation. A one-stage operation is recommended for patients with a well-organized fistula and with no systemic infection who are in good general health.
A diverting colostomy, with or without urinary diversion, may be used in cases of advanced cancer for palliation or severe radiation damage as a long-term solution.
A review of the literature reveals one reported case of a colovesical fistula treated with transurethral resection with no evidence of recurrence in more than 2 years of follow-up.
Several reports suggest that laparoscopic resection and reanastomosis of the offending bowel segment is possible as a minimally invasive treatment.
Preoperative details: The usual preoperative medical evaluation and staging (in the case of suspected or diagnosed cancer) should be performed. In addition, a mechanical and antibiotic bowel preparation is performed preoperatively. At this author's institution, this includes an oral gavage with GoLYTELY (or its equivalent), tap water or soapsuds enemas until clear, and oral neomycin and erythromycin base. A second-generation cephalosporin is generally administered intravenously for antibiotic prophylaxis. Other variations on this bowel preparation have also been used successfully. The goal is to clear as much fecal content and as many bacteria as possible before resection to allow uncomplicated healing after successful surgery.
Intraoperative details: The colon is mobilized proximal and distal to the fistula. Pinching the colon off the bladder by blunt dissection may be possible, but usually, this requires a careful and tedious sharp dissection.
Diverticulitis is generally managed by bluntly dissecting the colon from the bladder, resecting the colon, and performing a primary anastomosis. Often, when the colon is freed from the bladder, an actual opening in the bladder is not observed. Many of these fistulous tracts are tiny, and if the opening into the bladder is not apparent, the bladder can be distended with infusion via a catheter of fluid that contains methylene blue. A large visible opening can be closed in 2 layers with interrupted absorbable sutures. Smaller lesions can be left alone.
A report of fibrin sealant closure of a contaminated fistula has been described, with no evidence of fistula recurrence at 4 years. The diseased bowel is resected, and a primary anastomosis is usually created. If suitable omentum is available, it may be interposed with tacking sutures between the bladder and bowel. Extensive inflammatory involvement of the bladder wall, once thought to require partial bladder resection, does not necessarily require removal of any part of the bladder. Excision of involved bladder tissue is necessary only for carcinoma.
To avoid tumor spillage, a circumscribing incision around the tumor mass and through the bladder wall is undertaken. Frozen sections of the margins are sent to the histology laboratory for analysis. Further resection is undertaken as indicated, and if results of frozen section analysis eventually return as negative, a multilayered closure and omental interposition are performed. This may help reduce postoperative complications and the risk of recurrence.
Surgery for radiation-induced fistulae can be difficult. In severe cases, the colorectal and adjacent organs are matted together with no natural planes, making mobilization and resection hazardous. In this situation, performing a diverting proximal colostomy or ileostomy is advisable. In milder cases where resection can be performed safely, a descending anal anastomosis, with or without a colonic J pouch, can be performed.
The urinary system can be left intact, with catheter drainage. Healing in this situation is slow and may require longer periods of catheterization. In situations where healing is not expected, a transverse colon conduit can often be successful at restoring quality of life. Ileal and sigmoid conduits are less favorable because they often have been in the field of radiation.
Most colovesical fistulae enter the bladder well away from the trigone. When fistulae enter the bladder close to the trigone, take care to avoid periureteral dissection. If identification is difficult, ureters can be stented intraoperatively or observed either endoscopically or through the vesicotomy after intravenous injection of indigo carmine or methylene blue. A report describes fibrin seal closure of a contaminated fistula with no evidence of recurrence after 4 years of observation.
Surgical management of the bladder is varied. The technique of bladder repair (ie, excision versus oversewing) is not critical, and small defects do not require any particular repair. As long as adequate bladder drainage is provided, variations in bladder management are unlikely to have an impact on the patient outcome. When available, omentum should be applied to the serosal surface. No difference in patient outcome has been observed with regard to the type of suture employed, the number of layers of closure, or the type of postoperative bladder drainage.
Postoperative details: A nasogastric tube can be left in place until bowel function returns. More rapid return of bowel function may be obtained with the use of rectal suppositories (for high nonrectal fistulae). Concomitant treatment with parenteral or low-residue enteral feeding may be appropriate. Treatment with steroids is continued in patients with Crohn disease, but slower healing of the bladder should be anticipated. Bladder drainage is continued, taking care to assure low-pressure unobstructed flow of urine.
Follow-up care: After repair of the fistula for benign disease, the urinary catheter is left in place for 5-7 days or longer. The patient remains on appropriate antibiotics (ie, based on preoperative culture and sensitivity). At the next observation, a repeat urine culture and a sensitivity evaluation are obtained. Gravity cystography can be performed to confirm healing before catheter removal. Antibiotics are continued for 24-48 hours after catheter removal until the culture results are documented as negative.
Thereafter, the primary enteric process is treated as indicated, and the patient is observed periodically, using urinalysis and cultures as indicated. The patient is usually aware of the symptoms of recurrence, and he/she should be encouraged to return early if any symptoms of infection, pneumaturia, or fecaluria occur.
In the case of cancer resection, observational colonoscopy and CT scanning are obtained as indicated by tumor histology and stage. Periodic cystoscopy may also be indicated because local recurrence may be possible in the detrusor muscle. Cystoscopy is especially important if the margin status of the tumor was questionable.
Certainly, any hematuria in the postoperative period should be carefully evaluated with upper tract imaging and cystoscopy.
In a 1998 study, Woods encountered a 3.5% operative mortality rate and a complication rate of 27%. Fistula recurrences have been reported in 4-5% of patients. Most other studies have not found operative mortality rates that are this high, except in the cases of severely ill patients with other significant medical problems.
Short-term complications include the usual potential problems after general surgery (eg, fever, atelectasis, slow return of bowel function, catheter-related UTI, deep vein thrombosis [DVT], wound breakdown and infection). These complications are largely preventable with measures that include incentive spirometry, early ambulation, a thromboembolic hose or anticoagulation in susceptible patients, and appropriate wound closure techniques.
Long-term complications include persistent bladder leak (usually observed after radiotherapy for carcinoma), recurrence of a fistula (also more likely after radiotherapy), pelvic/abdominal abscess (from a leaking anastomosis), cutaneous fistulization (also from a leaking anastomosis), and bowel obstruction (from adhesions or recurrent diverticulitis).
Consider recurrent cancer in the abdomen or previously involved bladder wall when patients return with signs of bowel obstruction, new hematuria, or irritative voiding. Repeat CT scanning, serum carcinoembryonic antigen (CEA) measurement, urine culture and cytology, and cystoscopy are indicated in these settings.
In a retrospective record review of 76 patients diagnosed with enterovesical fistula over a 12-year period, no statistically significant difference in the complication rate existed between groups treated with single-stage repair and groups treated with multistage repair.
In general, for patients with non–radiation-induced or cancer-induced fistulae, the overall outcome and prognosis are excellent. Such patients usually respond well to resection of the diseased colon and have no significant urinary sequelae.
The prognosis for patients with colon carcinoma and fistulization is less favorable because the involvement of the bladder usually heralds a more aggressive tumor that often is metastatic at the time of detection.
Radiation-induced fistulae are more likely to recur, but the long-term patient prognosis may be better if the malignancy for which the radiation was administered has been controlled.
Future treatment of typical enterovesical fistulae may focus on development and refinement of laparoscopic techniques to allow resection with a minimal hospitalization. New modalities in neoadjuvant chemotherapy may allow further bladder preservation strategies. Trends in radiation oncology that permit minimization of collateral organ damage (eg, conformal external beam radiotherapy) and the use of tumor-specific radiosensitizing agents may be highly useful in preventing radiation-induced fistulae. Improved surgical techniques, including laparoscopic procedures that greatly enhance visualization of the operative field, hold promise for fewer fistula-related complications of gynecologic and urologic procedures.