Practice Essentials
An enterovesical fistula (EVF), also known as a vesicoenteric or intestinovesical fistula, occurs between the bowel and the bladder. [1] Normally, the urinary system is completely separated from the alimentary canal. Connections may result from any of the following:
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Incomplete separation of the two systems during embryonic development (eg, failure of the urorectal septum to divide the common cloaca)
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Infection
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Inflammatory conditions
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Cancer
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Trauma or foreign body
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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. Fistulas 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 fistulas. [2]
History of the Procedure
As early as the second century CE, Rufus of Ephesus described fistulas between the bowel and the bladder. The common causes of acquired vesicoenteric fistulas 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 fistulas "might be cured by a course of Bristol water and ass's milk." [3] 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 fistulas, also known as enterovesical or intestinovesical fistulas, occur between the bowel and the bladder. Vesicoenteric fistulas can be divided into four primary categories based on the bowel segment involved, as follows [4] :
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Colovesical (70%)
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Rectovesical (including rectourethral) (11%)
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Ileovesical (16%)
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Appendicovesical (7%)
Colovesical fistula is the most common form of vesicointestinal fistula and is most often located between the sigmoid colon and the dome of the bladder. [4] Most colovesical fistulas result from diverticular disease. [5] Rectourethral and rectovesical fistulas are observed in the postoperative setting, such as after prostatectomy; as a consequence of chronic infection or tissue destruction that accompanies advanced pressure injuries; or in the setting of acute infections such as Fournier gangrene.
Epidemiology
Frequency
Colovesical fistulas are the most common type of fistulous communication between the bowel and the urinary bladder. The relative frequency of colovesical fistulas is difficult to ascertain because of the numerous potential etiologies, including multiple disease processes and surgical procedures. [6]
The incidence of fistulas 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. [7]
Colovesical fistulas 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 fistulas (typically iatrogenic, such as enterovaginal, ureterovaginal, and vesicovaginal) are more common than colovesical fistulas. [7] Women who present with colovesical fistulas 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 the intestinal pathology.
Pathophysiology
Fistulas may be either congenital or acquired (eg, inflammatory, surgical, neoplastic). Congenital vesicoenteric fistulas are rare and are often associated with an imperforate anus.
Inflammatory pathophysiology
Approximately 80% of enterovesical fistulas are associated with inflammatory conditions. [4] Diverticulitis accounts for approximately 50%-70% of enterovesical fistulas, almost all of which are colovesical. A phlegmon or abscess is a risk factor for fistula formation. [8] This complication occurs in 2%-4% of cases of diverticulitis, although referral centers have reported a higher incidence. [9]
Crohn disease accounts for approximately 10% of vesicoenteric fistulas and is the most common cause of an ileovesical fistula. Ileovesical fistulas 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. [10]
Less-common inflammatory causes of colovesical fistulas include Meckel diverticulum, [11] genitourinary coccidioidomycosis, [12] and pelvic actinomycosis. [13] In addition, case reports have described appendicovesical fistulas as a complication of appendicitis. [14, 15, 16, 17] Enterovesical fistula formation due to lymphadenopathy associated with Fabry disease has been reported. [18]
Rarely, the inflammatory process originates in the bladder, as noted in a case report from Spain of bladder gangrene that caused a colovesical fistula in a patient with diabetes mellitus. [19] Other case reports have demonstrated fistula formation in the setting of chronic outlet obstruction due to benign prostatic hypertrophy, with the formation of a large bladder stone and recurrent infections. [20]
Malignant pathophysiology
Malignancy accounts for up to 20% of vesicoenteric fistulas and is the second most common cause of enterovesical fistula. Rectovesical fistula is the most common presentation, as rectal cancer is the most common colonic malignancy resulting in fistula formation. [21] 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. [22] Occasionally, carcinomas of the cervix, prostate, and ovary are implicated, and cases involving small-bowel lymphoma have been reported. [23]
Although malignancy is the second most common cause of enterovesical fistula formation, such cases have become uncommon because most carcinomas are diagnosed and treated prior to this advanced stage.
Iatrogenic pathophysiology
Iatrogenic fistulas 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 fistulas. [24, 25] 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 fistulas usually develop years after radiation therapy for a gynecologic or urologic malignancy. The incidence of radiation-induced fistula associated with gynecologic cancers (most commonly cervical cancer) is approximately 1%, many of which are rectovaginal or vesicovaginal. [26]
Fistulas 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 fistulas 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, fistulas due to cytotoxic therapy have been reported. One case involved a patient undergoing a CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) regimen for non-Hodgkin lymphoma. [27] Another involved enterovesical fistula as a result of neutropenic enterocolitis (a complication of chemotherapy) in a pediatric patient with acute leukemia. [28]
Traumatic pathophysiology
Urethral disruption caused by blunt trauma or a penetrating injury can result in fistulas, but these fistulas 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 review of complications of penetrating rectal and bladder injuries, fistula formation occurred only in the presence of bowel and bladder injuries. [29] 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 fistulas. [30, 31, 32, 33, 34]
Presentation
The presenting symptoms and signs of enterovesical fistulas 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 fistulas may be described as Gouverneur syndrome—namely, suprapubic pain, frequency, dysuria, and tenesmus. Other signs include the following [35] :
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Abnormal urinalysis findings
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Malodorous urine
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Pneumaturia
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Debris in the urine
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Hematuria
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UTIs
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. In dog models, surgically created colovesical fistulas are tolerated well in the absence of obstruction. [36]
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, Clostridioides 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. [21]
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. [21]
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 fistulas. Fistulas should be repaired in patients with any of the following:
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Abdominal pain
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Dysuria
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Malodorous urine
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Incontinence
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Urinary outlet obstruction
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Recurrent cystitis
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Bouts of sepsis
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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 fistulas primarily result from sigmoid diverticular disease. Ileovesical fistulas are most likely associated with Crohn disease. Rectovesical fistulas are more commonly due to trauma, surgery, or malignancy. Appendicovesical fistulas 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 of enterovesical fistula. Patients with those contraindications may be served better with medical therapy or less-invasive diversions (eg, colostomy, ureterostomy, percutaneous drainage).
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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 the site of the vesicoenteric fistula.
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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). 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.
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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.
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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 photo, and some remnant mucus threads are adherent at the bottom.
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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 inflammation is present.
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Colovesical fistula identified on CT scan in a patient with diverticular disease and fecaluria. Arrow – fistula, B – bladder, C – sigmoid colon with diverticula.
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Colovesical fistula visualization on sagittal MRI. Arrow – fistula, B – bladder, C – sigmoid colon.
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Operative view from superior and anterior showing the bladder (B) and colon (C) with area of erythema at the site surrounding the fistula.
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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.
