Colovesical Fistula:
A Complete Clinical Guide
A colovesical fistula is an abnormal channel that forms between the colon and the bladder. This guide covers everything you need to know, from causes and symptoms through diagnosis, surgery, and recovery.
Medically reviewed by
Colorectal Surgery Specialists | Updated May 2026
What Is a Colovesical Fistula?
A colovesical fistula (CVF) is an abnormal tunnel-like channel that forms between the colon and the urinary bladder. This connection allows colonic contents, including bacteria, gas, and fecal material, to pass directly into the bladder, an organ that under normal circumstances is sterile.
A fistula is not a disease in itself but a complication of an underlying condition. The colovesical fistula is the most common type of enterovesical fistula, accounting for approximately 50-70% of all enterovesical fistulas.
The fistula most commonly forms between the sigmoid colon and the dome of the bladder, as these two structures lie immediately adjacent to each other in the pelvis. In females who have a uterus, the uterus sits between the colon and bladder, providing a natural physical barrier, which helps explain why males are approximately three times more likely to develop this condition.
Most cases are diagnosed in adults between the ages of 55 and 75 years, coinciding with the peak incidence of common underlying causes such as diverticular disease and colorectal cancer.
Key Anatomy
The colon is the longest part of the large intestine and absorbs water and electrolytes from undigested food. The bladder is a muscular hollow organ that stores urine produced by the kidneys. Under normal circumstances, these two organs are completely separated by tissue layers.
Types of Enterovesical Fistula
Enterovesical fistulas are classified according to the segment of the intestinal tract involved in the abnormal connection with the bladder. Understanding the type influences the surgical approach and prognosis.
Colon -> Bladder
Most common (50-70%)
Typically involves the sigmoid colon and bladder dome. Most commonly caused by diverticular disease.
Rectum -> Bladder
Less common
Involves the rectum rather than the colon. Often related to pelvic malignancy or radiation injury.
Ileum -> Bladder
Uncommon
Involves the small bowel (ileum). Often associated with Crohn's disease or prior abdominal surgery.
Appendix -> Bladder
Rare
A rare type usually arising from appendiceal abscess or perforated appendicitis.
Note on terminology:The terms "enterovesical fistula" and "intestinovesical fistula" are broader terms that encompass all fistulas between any part of the intestinal tract and the bladder. "Colovesical fistula" specifically refers to those involving the colon.
Symptoms of Colovesical Fistula
The symptoms of a colovesical fistula arise primarily because colonic bacteria, gas, and fecal material gain entry into the normally sterile bladder. The classic triad of symptoms is pneumaturia, fecaluria, and recurrent urinary tract infections.
Because urinary symptoms dominate the clinical picture, colovesical fistula is frequently misdiagnosed initially as a urinary tract infection or bladder problem.
Cardinal Symptoms
Pneumaturia
Most CharacteristicThe passage of gas through the urethra during urination. Patients often describe "bubbly urine" or a "hissing" sensation. Pneumaturia is the single most characteristic symptom and is present in up to 70% of cases.
Fecaluria
Highly SpecificThe passage of fecal matter, visible stool particles, or brown foul-smelling material in the urine. Fecaluria is present in approximately 40-50% of cases and is highly specific for an enterovesical fistula.
Recurrent Urinary Tract Infections
Very CommonRepeated episodes of urinary tract infection that do not respond adequately to antibiotic therapy, or that recur soon after treatment ends. Polymicrobial infection should raise suspicion for an enterovesical fistula.
Additional Symptoms
Dysuria
Painful or burning urination due to bladder inflammation
Urinary urgency and frequency
Feeling of needing to urinate urgently or more often than usual
Haematuria
Blood in the urine, related to bladder mucosal irritation
Suprapubic or lower abdominal pain
Pain arising from the inflamed bladder or pelvic structures
Cloudy or foul-smelling urine
Due to presence of bacteria and intestinal contents in the bladder
Diarrhoea or altered bowel habit
Reflecting the underlying bowel pathology driving the fistula
Nausea and general malaise
Especially when infection progresses toward systemic illness
Unintentional weight loss
May indicate an underlying malignancy as the cause
Causes & Risk Factors
A colovesical fistula is usually the consequence of an underlying disease process that causes inflammation, abscess formation, or direct invasion of adjacent pelvic structures. Identifying the cause shapes treatment.
Diverticular Disease (Diverticulitis)
Diverticular disease is the most common cause. When a diverticulum becomes inflamed and forms a pericolic abscess, the abscess can rupture or erode directly into the adjacent bladder wall, creating a fistulous tract.
Colorectal Carcinoma
Colorectal cancer is the second most common cause. A tumour in the sigmoid colon or rectum can grow directly into the bladder wall, creating a malignant fistula and changing the surgical approach.
Crohn's Disease
Crohn's disease causes full-thickness inflammation of the bowel wall that can penetrate to adjacent organs. Crohn's-related fistulas require medical control of underlying inflammation before or alongside surgery.
Radiation Injury
Pelvic radiation therapy can cause progressive ischaemic injury to pelvic structures over months to years. Radiation-related fistulas are particularly challenging to repair surgically.
Other Less Common Causes
Risk Factors
- Male sex
- Age over 55 years
- History of diverticular disease
- History of colorectal or pelvic cancer
- Prior pelvic radiation therapy
- Inflammatory bowel disease
- Prior abdominal or pelvic surgery
- Immunosuppression
Diagnosis of Colovesical Fistula
Diagnosis can be challenging because the tract itself may be small and not directly visible on any single investigation. A combination of clinical assessment, laboratory tests, imaging, and endoscopic studies is commonly required.
The diagnosis should be suspected in patients with recurrent, polymicrobial UTIs that do not resolve with standard antibiotic therapy, especially when pneumaturia or fecaluria is present.
Laboratory & Urine Studies
May show white cells, bacteria, and sometimes fecal particles.
Polymicrobial growth with intestinal organisms is highly suggestive.
A non-invasive test in which ingested poppy seeds later appearing in urine confirm an enterovesical connection.
CT Scan (CT Cystography)
Often the investigation of choice. It can show air in the bladder, inflammation, abscess, and sometimes the fistulous tract.
Contrast is instilled into the bladder before CT to better define the tract.
Air within the bladder without recent instrumentation is strongly suspicious for an enterovesical fistula.
Cystoscopy
The fistula opening may be visible, but often only surrounding inflammation is seen.
Biopsy from suspicious bladder lesions helps rule out bladder malignancy.
Cystoscopy is important for excluding bladder cancer and planning repair.
Colonoscopy & Other Studies
Important to exclude colorectal cancer and assess diverticular disease or Crohn's colitis.
May provide complementary anatomical information, though it is less sensitive than CT.
Useful in complex, recurrent, radiation-related, or malignancy-suspected cases.
Treatment Options
The definitive treatment for most colovesical fistulas is surgical repair. The approach depends on the underlying cause, patient fitness, inflammation, and whether malignancy is present.
Conservative Management
Reserved for a minority of patients where surgical risk is prohibitively high. It aims to control symptoms and prevent complications rather than cure the fistula.
- Antibiotic therapy to manage recurrent UTIs
- Nutritional support and optimisation
- Medical treatment of the underlying cause
- Urinary catheterisation in selected cases
- Careful monitoring for deterioration or malignancy
Surgical Management
Surgery is the gold standard and the only curative option. The goals are to remove diseased colon, repair the bladder defect, and restore intestinal continuity when appropriate.
- Resection of the involved sigmoid colon
- Primary colorectal anastomosis when safe
- Repair or closure of the bladder opening
- Temporary diverting colostomy if needed
- Laparoscopic or open approach depending on case complexity
Malignant vs Benign Fistulas
When a colovesical fistula is caused by colorectal cancer, surgery must follow oncological principles and is often more extensive than repair of a benign diverticular fistula.
Surgical Procedures in Detail
One-Stage Resection with Primary Anastomosis
Most Common (Benign)The diseased segment of sigmoid colon is removed, the bowel ends are joined, and the bladder opening is closed or allowed to heal with urinary catheter drainage for several days.
Hartmann's Procedure (Two-Stage)
Used in Complex CasesUsed when conditions are unfavourable for primary anastomosis, such as sepsis, severe inflammation, poor nutrition, or high operative risk. A temporary colostomy is created and may be reversed later.
Laparoscopic Approach
Increasingly PreferredFor selected patients, laparoscopic repair can reduce hospital stay, postoperative pain, wound complications, and time to normal activity while maintaining comparable outcomes.
Oncological Resection for Malignant Fistula
Cancer-Related FistulasWhen cancer is the cause, resection requires adequate margins, lymph node clearance, and sometimes en-bloc removal of involved bladder tissue.
Complications
Complications can arise from the fistula itself or from surgical treatment. Understanding these risks helps patients make informed decisions about care.
Disease Complications
Urosepsis
Colon bacteria entering the bladder and bloodstream can cause life-threatening systemic infection.
Chronic kidney disease
Repeated severe urinary tract infections can damage the kidneys over time.
Bladder stone formation
Chronic infection and fecal material can create conditions for stone formation.
Bladder wall thickening
Chronic inflammation may lead to fibrosis and reduced bladder function.
Nutritional deficiency
If small bowel is involved, malabsorption and weight loss can occur.
Surgical Complications
Anastomotic leak
Leakage where the two bowel ends are joined, requiring urgent management.
Wound infection
More common in colorectal surgery due to proximity to the bowel.
Fistula recurrence
Risk is higher in Crohn's disease or complex bladder repair.
Bladder dysfunction
Temporary urinary retention or incontinence may occur after repair.
Colostomy-related complications
Stoma prolapse, parastomal hernia, and need for reversal surgery can occur.
Outlook & Recovery
Prognosis depends primarily on the underlying causeand the patient's overall health. For benign causes, particularly diverticular disease, surgical outcomes are generally good.
For malignant fistulas, prognosis is determined by cancer stage, complete surgical resection, and response to adjuvant therapy.
Recovery Timeline
Intravenous fluids, pain management, early mobilisation, urinary catheter drainage, and gradual reintroduction of diet.
Discharge once bowel function returns and the patient can eat and mobilise. Catheter removal is usually planned after bladder healing is confirmed.
Gradual return to normal daily activities. Heavy lifting, strenuous exercise, and driving may be restricted initially.
Most patients recover well by 3 months. Those with temporary colostomy need reversal surgery later, extending total recovery time.
When to See a Doctor
Prompt medical evaluation is important. Early diagnosis leads to earlier treatment and better outcomes, especially if infection, malignancy, or kidney involvement is a concern.
Seek Urgent Medical Attention If You Experience:
Schedule a Medical Appointment If You Have:
- A history of diverticular disease and new urinary symptoms
- More than two urinary tract infections in 12 months
- Urinary symptoms with unexplained weight loss or bowel changes
- Known Crohn's disease with new urological complaints
- History of pelvic cancer or pelvic radiation with new urinary symptoms
Frequently Asked Questions
Common questions about colovesical fistula answered by clinical experts.
Medically Reviewed
Reviewed by Colorectal & General Surgery Specialists
The content on this page has been reviewed for clinical accuracy by colorectal and general surgery specialists. Information is drawn from peer-reviewed literature and current surgical guidance.
Last reviewed: May 2026 | This page is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional regarding your individual circumstances.