Colovesicular fistula

Approach to diagnosing Colovesicular fistula- A Medical Student Clinical Pearl

Emmanuel Hebert

Med 4, Dalhousie Medicine

Reviewed by Dr. Chris Doiron

Copyedited by Dr. Mandy Peach


54 y/o M presents with a bizarre presenting complaint at 10am Monday morning…

You enter the room to see a man in no apparent distress who tells you that for the past two days something that looks like feces is coming out of his penis. The patient went to the bathroom to urinate Sunday night and noted air coming out of his penis that felt as if he were passing flatus. He then noticed brown foul-smelling liquid upon urinating. There was no blood. He reports no suprapubic fullness, pain with urination, or urgency. He denies any abdominal or pelvic pain. He noted chills Sunday evening which resolved and have not returned after a single dose of acetaminophen 500mg.


Past Medical History:


Adenocarcinoma of rectum- 2019

Radiation Therapy- 2019

Partial Bowel resection with ileostomy and stoma- 2019

Reversion of ileostomy- 2020

Medications: Coversyl Plus

Allergies: Codeine, penicillin

Physical Examination:

Patient is comfortable and appears well. Vitals: HR 85; Temp 36.5; BP: 125/80; O2Sat99% on RA. Abdominal exam is unremarkable. There is no suprapubic or CVA tenderness on palpation. Pelvic exam reveals a penis with no discharge or tenderness.


Initial bloodwork:

  • WBC: 11×10^9/L
  • Hgb: 135
  • Plt: 300×10^9/L
  • Na: 135
  • K: 4.0
  • CRP: 80
  • Lactate: 1.0
  • Creatinine: 100
  • eGFR: N

Urinalysis: Grossly brown with + leukocytes, Nitrite positive and RBCs present


What is the differential diagnosis of pneumaturia?

  • Recent urinary tract instrumentation, catheterization.
  • Urinary tract infection with a gas forming organism (emphysematous cystitis).
  • Emphysematous pyelonephritis (rare) [1]
  • Colovesicular  and enterovesicular Fistula as a result of complicated Diverticulitis, Crohn’s Disease or Carcinoma of the Colon or Bladder

Colovesicular Fistula

Colovesicular and enterovesicular fistulas are defined as connections between the enteric lumen and the bladder. [2] There are many ways that tissue can develop a fistula but in the enteric system there are several common etiologies [3]:

  • Diverticulitis: 65–79% of cases
  • Cancer (mostly adenocarcinoma): 10–20%
  • Crohn’s Disease: 5-7%
  • Previous radiation, bowel surgery, perforated peptic ulcer, genitourinary coccidioidomycosis, pelvic actinomycosis, and appendicitis make up the remaining cases.

Symptoms of Colovesicular Fistula

Figure 1: Graphic showing the common symptoms of colovesicular fistula


The classic findings of enterovesicular and colovesicular fistulas known as Gouveneur’s Syndrome are suprapubic pain, frequency, dysuria, and tenesmus.

Notwithstanding, pneumaturia, fecaluria and recurrent UTIs are pathognomonic with over 75% of patients presenting with these three findings. [3]



Urinalysis (U/A) and culture can be useful on initial presentation to help guide diagnosis. In colovesicular fistula, U/A can reveal white blood cells and feces in the urine. Cultures will typically grow bacteria associated with the enteric system with E. coli being the most common pathogen (81% ). [3] (Note: E. coli is a common pathogen in the setting of an uncomplicated UTI thus E. coli growth does not necessarily mean the patient has a fistula)


It is important to assess for evidence of sepsis in any patient with suspected colovesicular fistula. If the patient displays signs of fever and/or shock, blood and urine cultures and other labs to guide resuscitation and management are indicated. There are no blood tests that help definitively diagnose a colovesicular fistula.


When the clinical suspicion of colovesicular fistula is high, computed tomography (CT) of the abdomen and pelvis with oral/rectal contrast but without IV contrast is indicated. IV contrast is excreted by kidneys and can appear in the bladder confusing the origin of the contrast. Rectal contrast, however, should not appear in the bladder and its presence can help confirm the diagnosis. CT findings indicative of colovesicular fistula include air in the bladder/ureters, visualization of the fistula tract, oral/rectal contrast in the bladder, and bladder thickening adjacent to a thickened loop of bowel. [3]

Point of care ultrasound may identify echogenic material (fecal material), reverberation artifact indicative of gas within the bladder or thickened bowel abutting the bladder though is not generally nor should be considered a modality for the diagnosis of colovesicular fistula.

MRI provides excellent resolution of a fistula tract and potential underlying pathology however, given lack of access and the associated time and financial costs, CT remains the modality of choice for the diagnosis of colovesicular fistula in the emergency department. [3]

Figure 2: CT Abdomen-Pelvis revealing pneumoureter in the left image and the colovesicular tract in the right image.


The definitive management of a colovesicular fistula is surgical repair. Timing is dependent on several factors including hemodynamics at presentation, patient comorbidities, and etiology of the fistula (diverticulitis vs malignancy). In rare cases, conservative management may be considered if the patient is too frail for surgery. Septic patients should be resuscitated as per sepsis guidelines while stable patients should receive broad spectrum antibiotics with ciprofloxacin and metronidazole or amoxicillin-clavulanate being common regimens. Surgical consultation is recommended in all patients after initial resuscitation and imaging. [2]

Back to the case:

CT abdomen-pelvis was performed which showed air in the ureter and bladder as well as a tract connecting the sigmoid colon to the bladder. General Surgery was consulted and Piperacillin/Tazobactam 3.375g IV q6h was started. As the patient was stable, surgery asked that the patient be held in the ED until they could be seen latter in the day.

Two Hours Later

• On reassessment, patient appeared unwell and visibly diaphoretic. He was febrile with a temp of 38.5, a HR of 110 and a BP of 100/70. Repeat labs showed a white count of 14 and a lactate of 2.5.
• Diagnosis of septic shock was made and resuscitation started.
• Surgery was notified who opted to bring the patient to the OR for emergent exploratory laparotomy.

In the OR:

• The bladder was attached to the sigmoid colon via a thick adhesion. The surgeon had difficulty discerning what was bladder and what was intestine.
• Intestine was resected and an ileostomy was placed with stoma.
• Patient tolerated procedure well and was admitted to ICU for monitoring.

Figure 3: Laparoscopic View of bowel adhered to the bladder


Key Takeaways

  • Most colovesicular fistulas are the result of complicated diverticulitis.
  • Pneumaturia is highly suggestive for enterovesicular fistula in the absence of recent bladder instrumentation.
  • CT abdomen/pelvis with oral and rectal contrast without IV contrast is the imaging modality of choice.
  • Patients can go from stable to septic shock quickly.
  • The definitive management is surgical [2]




  1. Youssef S. Tanagho, Jonathan M. Mobley, Brian M. Benway, Alana C. Desai, “Gas-Producing Renal Infection Presenting as Pneumaturia: A Case Report”, Case Reports in Medicine, vol. 2013, Article ID 730549, 3 pages, 2013.
  2. Granieri, S., Sessa, F., Bonomi, A., Paleino, S., Bruno, F., Chierici, A., Sciannamea, I. M., Germini, A., Campi, R., Talso, M., Facciorusso, A., Deiana, G., Serni, S., & Cotsoglou, C. (2021). Indications and outcomes of enterovesical and colovesical fistulas: systematic review of the literature and meta-analysis of prevalence. BMC surgery21(1), 265.
  3. Tomasz Golabek, Anna Szymanska, Tomasz Szopinski, Jakub Bukowczan, Mariusz Furmanek, Jan Powroznik, Piotr Chlosta, “Enterovesical Fistulae: Aetiology, Imaging, and Management”, Gastroenterology Research and Practice, vol. 2013, Article ID 617967, 8 pages, 2013.
  4. Kavanagh, P. Neary, J. D. Dodd, K. M. Sheahan, D. O’Donoghue, and J. M. P. Hyland, “Diagnosis and treatment of enterovesical fistulae,” Colorectal Disease, vol. 7, no. 3, pp. 286–291, 2005.



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