Overview
Definition:
A colovesical fistula is an abnormal communication between the colon and the urinary bladder, leading to the passage of fecal material into the bladder or urine into the colon.
Epidemiology:
Most commonly occurs in older individuals, often associated with inflammatory bowel disease (Crohn's disease being the most frequent cause), diverticulitis, or malignant tumors
Malignancy accounts for a significant percentage in some series.
Clinical Significance:
Colovesical fistulas pose significant challenges due to recurrent urinary tract infections, fecuria (feces in urine), pneumaturia (gas in urine), sepsis, and malnutrition, necessitating timely and accurate surgical intervention to restore normal anatomy and function and prevent life-threatening complications.
Clinical Presentation
Symptoms:
Recurrent urinary tract infections with unusual pathogens
Passage of gas or stool from the urethra (fecuria/pneumaturia)
Suprapubic pain
Dysuria
Abdominal pain and distension
Fever and chills if sepsis is present
Change in bowel habits.
Signs:
Tenderness in the suprapubic or lower abdominal region
Signs of infection or sepsis may be present
Rectal examination may reveal inflammatory masses or tenderness
Digital rectal examination might reveal fecal material in the vagina or urine if there is a rectovaginal fistula, though less common in colovesical
Palpable abdominal masses in cases of malignancy.
Diagnostic Criteria:
Diagnosis is primarily clinical, confirmed by imaging and endoscopic studies
The constellation of symptoms like fecuria and pneumaturia is highly suggestive
While no formal diagnostic criteria exist, a combination of suggestive symptoms, positive imaging findings, and visualization during endoscopy establishes the diagnosis.
Diagnostic Approach
History Taking:
Detailed history of bowel and bladder symptoms is crucial
Inquire about prior abdominal surgery, history of inflammatory bowel disease (especially Crohn's), diverticulitis, radiation therapy to the pelvis, and symptoms suggestive of malignancy
Focus on the onset, duration, and progression of fecuria, pneumaturia, and recurrent UTIs.
Physical Examination:
A thorough abdominal examination to assess for masses, tenderness, and distension
A digital rectal examination to assess for anal sphincter tone, rectal masses, and tenderness
In females, a pelvic examination is important to rule out rectovaginal or enterovaginal fistulas
Assess for signs of systemic illness like fever or jaundice.
Investigations:
Urinalysis and urine culture to identify infection and its causative organism
Cystoscopy to visualize the bladder lining, identify the fistula opening, and assess for inflammatory changes or tumors
Colonoscopy to visualize the colonic side of the fistula, assess for inflammation or malignancy, and rule out other colonic pathology
Imaging studies are key: CT scan of the abdomen and pelvis with oral and IV contrast is the investigation of choice, often demonstrating bowel wall thickening, abscesses, and the tract
Barium enema or water-soluble contrast enema can delineate the fistula tract
MRI can be useful for better soft tissue characterization, especially in complex cases or suspected malignancy
Fistulography may rarely be needed
A simple methylene blue test in the bladder can confirm communication if urine is seen exuding from the rectum, though this is less common in colovesical fistulas.
Differential Diagnosis:
Urinary tract infections without fistula
Diverticulitis with contained perforation
Inflammatory bowel disease flares
Bladder diverticula
Bladder tumors
Pelvic abscesses
Pelvic actinomycosis
Ureteric obstruction with secondary infection
Simple uncomplicated cystitis or pyelonephritis.
Management
Initial Management:
Initial management focuses on sepsis control and nutritional support
Broad-spectrum intravenous antibiotics are administered to cover aerobic and anaerobic organisms
Fluid resuscitation is initiated for dehydration or sepsis
Nutritional optimization is important, especially if there is malabsorption or significant inflammation
If an abscess is present, percutaneous drainage is indicated.
Medical Management:
Antibiotics are the cornerstone of medical management, tailored to culture and sensitivity results
For Crohn's disease, medical management with anti-inflammatory agents, immunosuppressants, or biologics may be initiated or continued, but typically does not achieve fistula closure alone
Stricture management may be required.
Surgical Management:
Surgery is generally required for definitive closure of colovesical fistulas
The surgical approach depends on the underlying etiology and the extent of disease
Common procedures include: Bowel resection (segmental colectomy or colon resection) with primary anastomosis or stoma formation, depending on bowel contamination and anastomosis viability
Bladder resection or partial cystectomy if there is extensive bladder involvement or tumor
Excision of the fistula tract
Repair of bladder defect with primary closure
Penrose drains are often placed for pelvic drainage
For benign fistulas, bowel diversion (colostomy) may be temporary to allow healing, with subsequent reanastomosis
For malignant fistulas, the aim is complete oncologic resection, which may involve more extensive organ resection (e.g., partial cystectomy, ureteric reimplantation, hysterectomy in females).
Supportive Care:
Intravenous fluid therapy
Pain management
Nutritional support, including parenteral nutrition if significant bowel resection or malabsorption is expected
Close monitoring for signs of infection, bleeding, or anastomotic leak
Postoperative urinary catheterization is essential to protect the bladder repair and reduce bladder pressure
Stoma care education if a stoma is created.
Complications
Early Complications:
Anastomotic leak
Wound infection
Intra-abdominal abscess
Sepsis
Hemorrhage
Urinary retention
Persistent fecuria or pneumaturia
Bowel obstruction.
Late Complications:
Fistula recurrence
Stricture formation at the anastomosis or bladder neck
Chronic pelvic sepsis
Enterovesical fistula recurrence
Adhesions
Bladder stones
Incisional hernia.
Prevention Strategies:
Adequate bowel preparation before surgery
Meticulous surgical technique to excise the fistula tract and healthy tissue margins
Secure bladder closure
Appropriate use of drains
Postoperative antibiotic prophylaxis
Careful monitoring for early signs of complications
Optimizing nutritional status preoperatively.
Prognosis
Factors Affecting Prognosis:
The underlying etiology is a major factor
benign fistulas generally have a better prognosis than malignant ones
The extent of inflammation, presence of abscesses, nutritional status of the patient, and the surgeon's experience also play a role
Successful surgical resection and reconstruction are key to good outcomes.
Outcomes:
With appropriate surgical management, the prognosis for benign colovesical fistulas is generally good, with high rates of cure and recurrence being low
Malignant fistulas have a poorer prognosis, often being palliated or managed with more extensive resections if feasible
Long-term quality of life can be significantly improved after successful repair.
Follow Up:
Close follow-up is essential, especially after surgery for inflammatory bowel disease or malignancy
This includes monitoring for signs of recurrence, infection, or complications such as strictures
Regular clinical assessments, urine cultures, and imaging may be required based on the etiology
For inflammatory conditions like Crohn's, long-term medical management is crucial.
Key Points
Exam Focus:
Etiologies of colovesical fistula (Crohn's, diverticulitis, malignancy)
Diagnostic triad: fecuria, pneumaturia, recurrent UTIs
Gold standard imaging: CT abdomen/pelvis with contrast
Surgical management principles: resection of diseased segment, excision of fistula tract, bladder repair
Importance of differentiating benign vs
malignant causes.
Clinical Pearls:
Always consider colovesical fistula in patients with recurrent UTIs, especially in the absence of typical urinary symptoms
A simple test: filling the bladder with methylene blue and observing for blue urine per rectum (less common for colovesical but classic for enterovesical)
CT scan is your best friend for initial diagnosis and planning
Be prepared to discuss staged procedures for severe Crohn's fistulas
Recognize that oncologic resection principles apply to malignant fistulas.
Common Mistakes:
Failing to consider colovesical fistula in the differential diagnosis of recurrent UTIs
Inadequate investigations leading to missed diagnosis
Performing limited surgery without addressing the underlying etiology (e.g., not resecting diseased bowel in Crohn's)
Inadequate bladder closure or leaving contaminated tissue
Ignoring nutritional status and sepsis control.