Enterovesical Fistula

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Background

Normally, the urinary system is completely separated from the alimentary canal. Connections may result from (1) incomplete separation of the two systems during embryonic development (eg, failure of the urorectal septum to divide the common cloaca), (2) infection, (3) inflammatory conditions, (4) cancer, (5) trauma or foreign body, or (6) iatrogenic causes (presenting either postoperatively or as a treatment complication). In the general practice of medicine, bowel disease that occurs adjacent to the bladder and erupts into it is the most common cause of misconnection of the two systems. Fistulae from the bowel to the ureter and the renal pelvis are also possible but uncommon in the absence of trauma, chronic infection, or surgical interventions. This article focuses on the more common causes, presentations, and treatments of enterovesical fistulae.[1]

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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."[2] Although more invasive, certainly less colorful, and possibly more palatable, a single-stage surgical approach is more commonly used today.

Problem

A fistula is an abnormal communication between two 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 rectourethral), (3) ileovesical, and (4) appendicovesical fistulae. 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 that accompanies massive decubiti, or in the setting of acute infections such as Fournier gangrene.

Epidemiology

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 of the numerous potential etiologies, including multiple disease processes and surgical procedures.[3]

The incidence of fistulae in patients with diverticular disease, the most common cause of colovesical fistula, is accepted to be 2%, although some referral centers have reported higher percentages. Only 0.6% of carcinomas of the colon lead to fistula formation.[4]

Colovesical fistulae are more common 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. In women, other types of fistulae (typically iatrogenic, such as enterovaginal, ureterovaginal, and vesicovaginal) are more common than colovesical fistulae.[4] Women who present with colovesical fistulae are commonly older and/or have a history of hysterectomy. Uterine atrophy or absence may be predisposing etiologies.

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.

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.

Inflammatory pathophysiology

Diverticulitis accounts for approximately 50%-70% of vesicoenteric fistulae, almost all of which are colovesical. A phlegmon or abscess is a risk factor for fistula formation.[5] This complication occurs in 2%-4% of cases of diverticulitis, although referral centers have reported a higher incidence.[6]

Crohn disease accounts for approximately 10% of vesicoenteric fistulae and is the most common 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.[7]

Less-common inflammatory causes of colovesical fistulae include Meckel diverticulum,[8] genitourinary coccidioidomycosis,[9] and pelvic actinomycosis.[10] In addition, case reports have described appendicovesical fistulae as a complication of appendicitis.[11, 12, 13, 14] Enterovesical fistula formation due to lymphadenopathy associated with Fabry disease has been reported.[15]

Rarely, the bladder is 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.[16] Additional case reports have demonstrated fistula formation in the setting of chronic outlet obstruction due to benign hypertrophy with the formation of a large bladder stone and recurrent infections.[17]

Malignant pathophysiology

Malignancy accounts for up to 20% of vesicoenteric fistulae and is the second most common cause of enterovesical fistula. Rectovesical fistula is the most common presentation, as rectal carcinoma is the most common colonic malignancy resulting in fistula formation.[18] Transmural carcinomas of the colon and rectum may adhere to adjacent organs and may eventually invade directly, causing development of a fistula. Transitional cell carcinoma of the bladder is the next most common malignancy-related pathology.[19] Occasionally, carcinomas of the cervix, prostate, and ovary are implicated, and incidents involving small-bowel lymphoma have been reported.[20]

Although malignancy is the second most common cause of enterovesical fistula formation, such an event is uncommon today because most carcinomas are diagnosed and treated prior to this advanced stage.

Iatrogenic pathophysiology

Iatrogenic fistulae are usually induced by surgical procedures, primary or adjunctive radiotherapy, and/or postprocedural 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.[21, 22] Unrecognized rectal injury at the time of radical prostatectomy is an uncommon but well-documented etiology of rectourethral fistula.

External beam radiation or brachytherapy to bowel in the treatment field can eventually lead to fistula development. Radiation-associated fistulae usually develop years after radiation therapy for a gynecologic or urologic malignancy. The incidence of radiation-induced fistula associated with gynecological cancers (most commonly cervical cancer) is approximately 1%, many of which are rectovaginal or vesicovaginal.[23]

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 are usually complex and often involve more than one organ (eg, colon to bladder). Because of improvements in radiotherapy techniques, the incidence of this complication is decreasing. Although rare, fistulae due to cytotoxic therapy have been reported in a patient undergoing a CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) regimen for non-Hodgkin lymphoma.[24]

Traumatic pathophysiology

Urethral disruption caused by blunt trauma or a penetrating injury can result in fistulae, but these fistulae are typically rectourethral in nature. Penetrating abdominal or pelvic trauma, such as a gunshot wound, may result in fistula formation between both small and large bowel, including the rectum with the bladder. In a recent review of complications of penetrating rectal and bladder injuries, fistula formation occurred only in the presence of bowel and bladder injuries.[25] Foreign bodies in the bowel (eg, swallowed chicken bones or toothpicks) and peritoneum (eg, lost gallstone during laparoscopic cholecystectomy) have been reported as a cause of colovesical fistulae.[26, 27, 28, 29, 30]

Presentation

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). The hallmark of enterovesical fistulae may be described as Gouverneur syndrome, namely, suprapubic pain, frequency, dysuria, and tenesmus. Other signs include abnormal urinalysis findings, malodorous urine, pneumaturia, debris in the urine, hematuria, and UTIs.[31]

The severity of the presentation also varies. Chronic UTI symptoms are common, and patients with enterovesical fistula frequently report numerous courses of antibiotics prior to referral to a urologist for evaluation. Urosepsis may be present and can be exacerbated in the setting of obstruction. It has been demonstrated in dog models that surgically created colovesical fistulae are tolerated well in the absence of obstruction.[32]

Pneumaturia and fecaluria may be intermittent and must be carefully sought in the history. Pneumaturia occurs in approximately 50%-60% of patients with enterovesical fistula but alone is nondiagnostic, as it can be caused by gas-producing organisms (eg, Clostridium species, 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. Patients may describe passing vegetable matter in the urine. The flow through the fistula predominantly occurs from the bowel to the bladder. Patients very rarely pass urine from the rectum.[18]

Symptoms of the underlying disease causing the fistula may be present. Abdominal pain is more common in patients with Crohn disease, but an abdominal mass is discovered in fewer than 30% of patients. In patients with Crohn disease who have a fistula, abdominal mass and abscess are more common.[18]

Indications

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/or pyelonephritis. Patients at high surgical risk may be treated with medical therapy and catheter drainage but may ultimately require at least diverting surgery if symptoms persist. Patients with terminal cancer are often 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 is almost always intestinal and characteristic to particular intestinal segments that adhere to the bladder. The segments most commonly in proximity to the bladder include 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 are more commonly due to 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 to 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).

Laboratory Studies

Imaging Studies

CT scanning

CT scanning of the abdomen and pelvis is the most sensitive imaging test for detecting a colovesical fistula, and CT scanning should be included as part of the initial evaluation of suspected colovesical fistulae. CT scanning can demonstrate small amounts of air or contrast material in the bladder, localized thickening of the bladder wall, or an extraluminal gas-containing mass adjacent to the bladder. Three-dimensional reconstruction is useful when traditional axial and coronal images fail to demonstrate the anatomy in sufficient detail.[34] The images below show a series of CT scans.


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CT scan showing the adherence of the sigmoid colon to the lateral edge of the bladder.


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A lower cut of the CT scan from the related image. Note the sigmoid colon in direct proximity to the fistula and the air in the bladder.


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A CT scan one cut further inferiorly from the related images, showing the typical air pattern in the bladder and more obvious inflammatory changes at ....

Preoperative CT scanning in 9 consecutive patients with colovesical fistulae secondary to diverticulitis was accurately used to predict the presence and location of fistulae in 8 patients and led to suspicion in 1 patient.[35]

In another study, colovesical fistulae identified preoperatively with CT scanning in 12 patients were surgically confirmed in 11 of those patients. CT scanning was also used to exclude fistulae in 20 patients with uncomplicated acute diverticulitis.[36]

Avoiding oral contrast ingestion and having the patient evacuate rectally administered barium can enhance the value of CT scanning in the process of fistula identification.[37] CT scanning also plays an important role in preoperative surgical planning by demonstrating the extent and degree of pericolonic inflammation.

In another study, 3-dimensional CT scanning provided improved imaging of the anatomic relationships. Additionally, multidetector row CT urography is useful in identifying urinary tract abnormalities, including fistulae.[38] More sophisticated CT imaging modalities, such as CT colonoscopy, have been reported in the literature, but no clinical trials demonstrating a clinical benefit to this modality over traditional CT scanning have been published to date.[39]

Barium enema

Barium enema (BE) imaging is unreliable in revealing a fistula but is useful in differentiating diverticular disease from cancer. BE imaging can demonstrate the nature and extent of colonic disease. In a 1988 series, Woods et al used BE imaging to demonstrate fistulae in 42% of cases.[40]

Radiography of centrifuged urine samples obtained immediately after a nondiagnostic BE, called the Bourne test, may enhance the yield of the BE. Barium detected in the urine sediment confirms the presence of a fistula. In one study, the Bourne test results were positive in 9 of 10 patients. In 7 of these patients, the Bourne test finding was the only evidence of an otherwise occult colovesical fistula.[41]

Cystography

Cystography may demonstrate contrast outside the bladder but is less likely to demonstrate a fistula.

Radiographic signs have been described. The herald sign is a crescentic defect on the upper margin of the bladder that is visualized best in an oblique view. The herald sign represents a perivesical abscess. A "beehive on the bladder" sign is associated with the vesical end of the fistulous tract.[42]

Because of the superiority of CT scanning as a tool for diagnosis and treatment planning, plain cystography is no longer used in the evaluation of fistulae. CT scanning with rectal contrast only is the best diagnostic imaging modality.

Ultrasonography

Ultrasonography of colovesical fistulae has been described. In some instances, the fistula is easily identified, with no additional maneuvers needed.[43] Ultrasonographic examination of suspected fistulous sites has been enhanced with the technique of manual compression of the lower abdomen, which reveals an echogenic "beak sign" connecting the peristaltic bowel lumen and the urinary bladder.[44] As with cystography, ultrasonography is rarely used for primary imaging of fistulae.

Magnetic resonance imaging

MRI can be used to identify enterovesical fistulae. In a study of 25 patients with Crohn disease, 16 patients had enterovesical, deep perineal, or cutaneous fistulae. One false-negative result occurred in a patient who had a colovesical fistula.[45] Some authors recommend MRI evaluation in patients with Crohn disease given the presence of chronic inflammation and superior anatomic detail in relation to the anal sphincter. Another benefit is that this study does not expose the patient to additional radiation.[46]

T1-weighted images delineate the extension of the fistula relative to sphincters and adjacent hollow viscera and show inflammatory changes in fat planes.

T2-weighted images show fluid collections within the fistula, localized fluid collections in extra-intestinal tissues, and inflammatory changes within muscles.

MRI may be useful in identifying deep perineal fistulae but is not generally used in the routine workup of colovesical fistulae. In a study of 22 patients who presented with symptoms suggestive of colovesical fistula, MRI was performed in conjunction with cystoscopy. Afterward, 19 of the patients underwent laparotomy and repair. They found that MRI correctly identified 18 cases of fistula. Fistula was ruled out in the remaining patient. This data showed MRI to be a highly sensitive and specific study for colovesical fistula.

Although MRI is an excellent study, the increasing image quality of CT scanning, together with the high cost and limited availability of MRI, limit the practical application MRI as a diagnostic study for enterovesical fistulae.[47]

Diagnostic Procedures

Cystoscopy

Cystoscopy can be a helpful component of the diagnostic evaluation. Prior to the advancement of radiological diagnostic techniques, cystoscopy was considered to be the most reliable method of diagnosis.[31] The findings of this procedure can suggest the presence of a fistula, and cystoscopy can be used to evaluate for a possible malignancy.

Cystoscopy can be useful in paring down the list of differential diagnoses, and it enables the physician to obtain a biopsy of the fistula to check for malignancy. Localized erythema, papillary/bullous mucosal changes, and, occasionally, material oozing through an area are present in 80%-90% of diagnosed cases (see image below).


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An endoscopic view of colovesical fistula (upper right). Note the prominent edema and erythema characteristic of the fistula (ie, herald patch). Occas....

Inflammatory mucosal changes of edema and pseudopolyp formation have been termed the herald patch (see images below).[48]


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After a bladder wash-out, the fistula appears as a raised, edematous, sessile lesion in the bladder. The air bubble is observed at the top of the phot....


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The edema surrounding the fistula often extends for a considerable distance around the bladder wall. A cobblestone appearance is typical when chronic ....

Cystoscopy is used to initially diagnose fistulae in 30%-50% of cases. Cystoscopy findings are used to confirm enterovesical fistulae in 60%-75% of patients.

The presence of a localized area of edema and congestion is a typical finding in the early stages of a fistula. Bullous edema and mucosal papillomatous hyperplasia surround a fistula as it matures. Often, the fistula opening is not identified. Fecal material or mucus may be observed in the bladder.[48] An attempt may be made to catheterize the tract or inject contrast retrograde to confirm the presence of fistula using plain radiography or fluoroscopy. Lesions are most commonly observed on the dome of the bladder. A lesion on the left dome of the bladder is typically diverticular. A lesion on the right posterior wall or the right dome of the bladder is more likely associated with Crohn ileitis or an appendicovesical fistula.

Poppy seed test

The poppy seed test has recently proven to be a potentially helpful diagnostic tool. This test consists of administering 1.25 g of poppy seeds with 12 ounces of fluid or 6 ounces of yogurt to the patient. The urine is then collected for the next 48 hours and examined for poppy seeds.

In a recent trial, the accuracy of the poppy seed test was compared with CT scanning and nuclear cystography in 20 patients with surgically confirmed fistulae. The poppy seed test yielded a 100% detection rate, whereas CT scanning and nuclear cystography yielded rates of 70% and 80%, respectively. Because of the low cost of the test ($5.37 for the poppy seed test, $652.92 for CT scanning, $490.83 for nuclear cystography), this may serve as an excellent confirmatory test when fistula is suspected. An obvious problem with the poppy seed test is that it provides little detail as to the location and type of fistula present.[49]

When large areas of inflammation are appreciated or when abscess is involved, possible ureteral involvement should be considered, especially in the setting of any hydronephrosis. Preoperative evaluation with retrograde pyelography or intravenous pyelography (IVP) helps to demonstrate the extent of involvement for surgical repair.[50]

Colonoscopy

Colonoscopy, like BE, is not particularly valuable in detecting a fistula, but it is helpful in determining the nature of the bowel disease that caused the fistula and is typically part of the evaluation. Further, if malignancy is considered, colonoscopy should be performed preoperatively to allow for proper surgical planning.[48, 51]

Laparoscopy/laparotomy

The use of laparoscopy has been described in diagnosing a pediatric patient with an appendicovesical fistula.[13] Adult laparoscopy is commonly used for investigating abdominal pain in women and may become a more frequently used diagnostic tool in men. Exploratory laparotomy is used for diagnosis and therapy in all types of fistulae.

Histologic Findings

Histologic findings associated with a biopsy of fistulous sites are usually consistent with chronic inflammation. Even in the case of carcinoma, inflammation is the usual finding on the bladder side. In more advanced cases, mucin-producing adenocarcinoma may be identified. The differential diagnoses must include primary adenocarcinoma of the bladder or poorly differentiated urothelial carcinoma. The clinical scenario and laparotomy findings are usually helpful in determining the diagnosis.

Staging

Staging is appropriate when the etiology of the fistula is carcinoma. The staging of colorectal carcinoma is discussed in other Medscape Reference articles such as Imaging in Adenocarcinoma of the Colon, Rectal Carcinoma Imaging, and Colon Adenocarcinoma.

Medical Therapy

Nonsurgical treatment of colovesical fistulae may be a viable option in patients who cannot tolerate general anesthesia or in selected patients who can be maintained on prolonged antibacterial therapy for symptomatic relief.

Colovesical fistulae in patients with diverticulitis who are deemed to be a surgical risk have been managed conservatively. 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.[52] In another study, 6 patients who declined surgical intervention were monitored and were found to exhibit no significant changes in renal function, and urosepticemia was not documented.[53]

Recent interest in conservative management has led to animal experiments; these studies have shown that colovesical fistulae can be well tolerated in the absence of distal urinary or bowel obstruction (which could lead to sepsis).[54] If the 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. However, although some small studies have suggested conservative management as a reasonable option, no randomized controlled trials have supported conservative management, and careful selection with close follow-up is stressed.

Enterovesical fistulae due to Crohn disease are typically treated medically because of the chronic nature of the disease and the desire to avoid resection of bowel, if possible. Such fistulae may be managed with sulfasalazine, corticosteroids, antibiotics (eg, metronidazole), and 6-mercaptopurine. Medical therapy alone was continued in 6 patients 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.[55]

Newer agents continue to show improvement in medical management of enterovesical fistulae, especially in the setting of inflammatory disease. Infliximab is a chimeric monoclonal antibody against tumor necrosis factor (TNF)–alpha that may decrease the inflammatory response. Initially used for short-term symptom control, infliximab has demonstrated excellent results in fistula closure and maintenance of closure with medical treatment in the ACCENT I and II trials.[56]

Patients with advanced carcinoma may be treated with catheter drainage of the bladder alone or supravesical percutaneous diversion.

Surgical Therapy

Open surgery

Colovesical fistulae can almost always be treated with resection of the involved segment of colon and primary reanastomosis. Fistulae due to inflammation are generally managed with resection of the primarily affected diseased segment of intestine, with repair of the bladder only when large visible defects are present. The bladder usually heals uneventfully with temporary urethral catheter drainage. Suprapubic tube diversion is an option but is not necessary.[57]

Historically, staged procedures were used to treat colovesical fistula. 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 the bladder is emptying under low pressure. 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 in good general health who have a well-organized fistula and no systemic infection.[58]

A diverting colostomy, with or without urinary diversion, may be used as a long-term solution for palliation or severe radiation damage in cases of advanced cancer.

Endoscopic treatment

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.[59] With the development and advancements of hemostatic sealants, endoscopic injection of these materials is possible as a minimally invasive treatment. One concern would be the presence of foreign material in direct contact with the urine possibly acting as a nidus for stone formation. Few clinical trails have studied the application of these sealants, and this author does not recommend their use from an endoscopic approach.

Laparoscopic treatment[60]

Several reports suggest that laparoscopic resection and reanastomosis of the offending bowel segment is possible as a minimally invasive treatment.[61, 62, 63, 64] However, an abdominal incision is still required for removal of the affected intestinal segment intact for pathological assessment to rule out cancer.

Preoperative Details

The usual preoperative medical evaluation and staging (in the case of suspected or diagnosed cancer) should be performed. In addition, a preoperative mechanical and antibiotic bowel preparation is performed. At this author's institution, this includes an oral lavage with GoLYTELY (or its equivalent) and oral neomycin and erythromycin base. A second-generation cephalosporin is generally administered intravenously for antibiotic prophylaxis. Other variations of this bowel preparation, such as colonic irrigation with a Betadine solution, have also been used successfully. Surgeon preference dictates which is used. 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 with blunt dissection may be possible, but this usually requires a careful and tedious sharp dissection.[50]

Inflammatory fistulae

Diverticulitis is generally managed with blunt dissection of the colon from the bladder, resection of the colon, and primary anastomosis. Often, when the colon is freed from the bladder, the bladder does not contain an actual opening. Many of these fistulous tracts are tiny, and, if the opening into the bladder is not apparent, it can be demonstrated by distending the bladder via a catheter with fluid that contains methylene blue. A large visible opening can be closed in two layers with interrupted absorbable sutures. Smaller lesions can be left alone.[3]

Fibrin sealant closure of a contaminated fistula has been described, with no evidence of fistula recurrence at 4 years.[65] 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.[3]

Carcinoma-related fistulae

To avoid tumor spillage, a circumscribing incision around the tumor mass and through the bladder wall is made. Frozen sections of the margins are sent for histologic analysis. Further resection is undertaken as indicated, and, if frozen section analysis results eventually return as negative, a multilayered closure and omental interposition are performed. This may help reduce postoperative complications and the risk of recurrence.

Radiation-induced fistulae

Surgery to manage 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, diverting proximal colostomy or ileostomy is advisable. In milder cases in which resection can be safely performed, a descending anal anastomosis, with or without a colonic J pouch, can be performed.[48]

The urinary system can be left intact with catheter drainage, although healing in this situation is slow and may require longer periods of catheterization. Typically, surgical separation of the genitourinary and gastrointestinal systems is required, and staged operations are more commonly performed because of the poor quality of tissues. When healing is not expected, a transverse colon conduit is often successful at restoring quality of life. Ileal and sigmoid conduits are less favorable because they have often been in the field of radiation.[23]

Ureters

Most colovesical fistulae enter the bladder well away from the trigone. When fistulae enter the bladder close to the trigone, avoid periureteral dissection to prevent devascularization. If identification is difficult, ureters can be stented intraoperatively or observed either endoscopically or through the vesicostomy after intravenous injection of indigo carmine or methylene blue.

Bladder

Surgical management of the bladder varies. 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 affect the patient outcome. When available, omentum should be applied to the serosal surface . This may be particular beneficial in the setting of acute traumatic injury to both the bladder and rectum to aid in healing and may prevent future fistula formation.[25] To date, no studies have demonstrated that the choice of absorbable suture, the number of layers of closure, or the type of postoperative bladder drainage significantly affects outcomes.

Postoperative Details

A nasogastric tube can be left in place or the patient can continue on nothing by mouth (NPO) status until bowel function returns, depending on surgeon preference. The use of rectal stimulatory suppositories (for high nonrectal fistulae) may hasten the return of bowel function. 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 ensure low-pressure unobstructed urine flow.

Follow-up

After repair of fistulae caused by benign disease, the urinary catheter is left in place for 5-7 days or longer depending on the level of inflammation and size of the repair. The patient remains on appropriate antibiotics (ie, based on preoperative culture findings and sensitivity). At the next observation, a repeat urine culture with sensitivity is obtained. The author’s preference is to perform a gravity cystography with postdrainage films 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 periodically observed with urinalysis and cultures as indicated. The patient is usually aware of the symptoms of recurrence should be encouraged to return early upon any symptoms of infection, pneumaturia, or fecaluria.

If cancer resection is performed, observational colonoscopy and CT scanning are obtained as indicated based on tumor histology findings and stage. Periodic cystoscopy may also be indicated because of the possibility of local recurrence in the detrusor muscle. Cystoscopy is especially important if the margin status of the tumor is questionable.

Certainly, any hematuria in the postoperative period should be carefully evaluated with upper tract imaging and cystoscopy.

Complications

In a 1988 study, Woods et al reported a 3.5% operative mortality rate and a complication rate of 27%.[40] Fistula recurrences have been reported in 4%-5% of patients. Most other studies have not reported such high operative mortality rates, 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 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.

Outcome and Prognosis

In a retrospective record review of 76 patients diagnosed with enterovesical fistula over a 12-year period, the complication rate in those treated with single-stage repair was not statistically different from that in patients who underwent multistage repair.[66]

In general, the overall outcome and prognosis are excellent in patients with non–radiation-induced or cancer-induced fistulae. Such patients usually respond well to resection of the diseased colon and have no significant urinary sequelae.

The prognosis in 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 and Controversies

Future treatment of typical enterovesical fistulae may focus on development and refinement of minimally invasive surgical techniques, such as laparoscopic and robotic, to shorten recovery time and to potentially decrease hospital stay. The benefit and complications of preoperative ureteral stenting for intraoperative identification of the ureter may become a particular area of interest for clinical study. As of the latest review of this article, there is little clinical data to demonstrate the benefit of ureteral stents in preventing ureteral injury.

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.

Advancements in molecular biology and the development of medications to manipulate inflammatory mediators may eventually produce more specifically targeted therapies to decrease the risk of fistula formation in inflammatory conditions, particularly Crohn disease.

Given the low incidence of colovesical fistula, the development of and recruitment for prospective randomized studies is difficult.

Author

Joseph Basler, MD, PhD, Thomas P Ball Residency Education Professor, Urology Residency Program Director, Department of Urology, University of Texas Health Science Center at San Antonio; Chief, Section of Urology, Audie Murphy Veterans Affairs Hospital

Disclosure: Nothing to disclose.

Coauthor(s)

Angela Kamerer Schang, MD, Attending Urologist, McKay Urology

Disclosure: Nothing to disclose.

Ann S Fenton, MD, MPH, Chief, Urology Flight Surgical Services/SGOSU, 1st Fighter Wing Hospital, Langley Air Force Base; Consulting Staff, Department of Urology, Naval Medical Center Portsmouth; Assistant Professor, Eastern Virginia Medical School

Disclosure: Nothing to disclose.

Christopher H Cantrill, MD, Resident Physician, Department of Urology, University of Texas Health Sciences Center at San Antonio

Disclosure: Nothing to disclose.

Specialty Editors

Erik T Goluboff, MD, Professor, Department of Urology, College of Physicians and Surgeons, Columbia University College of Physicians and Surgeons; Director of Urology, Allen Pavilion, New York Presbyterian Hospital

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

J Stuart Wolf Jr, MD, FACS, The David A Bloom Professor of Urology, Director, Division of Endourology and Stone Disease, Department of Urology, University of Michigan Medical School

Disclosure: Nothing to disclose.

Chief Editor

Bradley Fields Schwartz, DO, FACS, Professor of Urology, Director, Center for Laparoscopy and Endourology, Department of Surgery, Southern Illinois University School of Medicine

Disclosure: Nothing to disclose.

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CT scan showing the adherence of the sigmoid colon to the lateral edge of the bladder.

A lower cut of the CT scan from the related image. Note the sigmoid colon in direct proximity to the fistula and the air in the bladder.

A CT scan one cut further inferiorly from the related images, showing the typical air pattern in the bladder and more obvious inflammatory changes at the site of the vesicoenteric fistula.

An endoscopic view of colovesical fistula (upper right). Note the prominent edema and erythema characteristic of the fistula (ie, herald patch). Occasionally, a whitish discharge with the consistency of toothpaste can be observed emanating from the orifice. The presentation of a vesicoenteric fistula includes the presence of air, fecal material, and polymicrobial recurrent urinary tract infection.

After a bladder wash-out, the fistula appears as a raised, edematous, sessile lesion in the bladder. The air bubble is observed at the top of the photo, and some remnant mucus threads are adherent at the bottom.

The edema surrounding the fistula often extends for a considerable distance around the bladder wall. A cobblestone appearance is typical when chronic inflammation is present.

CT scan showing the adherence of the sigmoid colon to the lateral edge of the bladder.

A lower cut of the CT scan from the related image. Note the sigmoid colon in direct proximity to the fistula and the air in the bladder.

A CT scan one cut further inferiorly from the related images, showing the typical air pattern in the bladder and more obvious inflammatory changes at the site of the vesicoenteric fistula.

An endoscopic view of colovesical fistula (upper right). Note the prominent edema and erythema characteristic of the fistula (ie, herald patch). Occasionally, a whitish discharge with the consistency of toothpaste can be observed emanating from the orifice. The presentation of a vesicoenteric fistula includes the presence of air, fecal material, and polymicrobial recurrent urinary tract infection.

A white mucinous exudate is observed emanating from the site of a colovesical fistula in a patient with both a sigmoid diverticular abscess and colon cancer.

After a bladder wash-out, the fistula appears as a raised, edematous, sessile lesion in the bladder. The air bubble is observed at the top of the photo, and some remnant mucus threads are adherent at the bottom.

The edema surrounding the fistula often extends for a considerable distance around the bladder wall. A cobblestone appearance is typical when chronic inflammation is present.

Colovesical fistula identified on CT scan in a patient with diverticular disease and fecaluria. Arrow – fistula, B – bladder, C – sigmoid colon with diverticula.

Colovesical fistula visualization on sagittal MRI. Arrow – fistula, B – bladder, C – sigmoid colon.

Operative view from superior and anterior showing the bladder (B) and colon (C) with area of erythema at the site surrounding the fistula.

Cystoscopic view of an anastomotic urethrorectal fistula that developed after radical prostatectomy. The patient remains asymptomatic with occasional pneumaturia. This is an uncommon complication of radical prostatectomy.