What is the appropriate diagnosis and treatment for an adult female patient presenting with stool leaking from the vagina, suspected to have a rectovaginal fistula?

Rectovaginal Fistula: Diagnosis and Management

Immediate Diagnosis

A woman presenting with stool leaking from the vagina most likely has a rectovaginal fistula, which requires prompt imaging confirmation with MRI pelvis (with and without IV contrast) as the preferred diagnostic modality, followed by surgical repair as definitive treatment. 1

Clinical Presentation

The pathognomonic symptoms that confirm this diagnosis include:

• Passage of stool, gas, or odorous mucopurulent discharge from the vagina (often confused with incontinence) 1
• Dyspareunia and perineal pain 1
• Recurrent vaginal infections 1

Critical Diagnostic Workup

Physical examination must determine whether the fistula is high (rectovaginal, above anal sphincter) or low (anovaginal, involving sphincter complex), as this dictates surgical approach. 1

Key examination findings to document:

• Location of internal opening (rectal side) 1
• Location of vaginal/vulvar opening 1
• Presence of multiple tracts or extensions (defines complexity) 1
• Associated abscess or active inflammation 1
• Anal sphincter integrity (damage requires concurrent sphincter repair) 2

Imaging Strategy

MRI pelvis without and with IV gadolinium contrast provides superior visualization of fistulous tracts and is essential for detecting active inflammation and abscesses. 1

Alternative imaging options when MRI unavailable:

• CT pelvis with IV contrast has comparable diagnostic utility for visualizing fluid collections and fistulous tracts 1
• Fluoroscopic vaginography demonstrates 79% sensitivity and 100% positive predictive value for tract identification 1
• Transrectal ultrasound shows 100% positive predictive value for anorectal opening and 93% for vaginal opening 1

Classification Determines Treatment

Simple fistulas (single tract, small, low position, no inflammation) versus complex fistulas (multiple openings, high position, associated abscess, inflammation, or prior radiation) require fundamentally different management approaches. 1, 2

Complex features requiring more aggressive intervention:

• Multiple external openings 1
• High anatomical position (above sphincter) 1
• Associated pain or fluctuation suggesting abscess 1
• Prior failed repair attempts 2
• Radiation-induced tissue damage 2
• Anal sphincter involvement 2

Microbiological Confirmation

Polymicrobial enteric flora with anaerobes (Bacteroides, fusobacteria, anaerobic cocci) on vaginal culture is highly specific for fistulous bowel communication. 1

This distinguishes true rectovaginal fistula from simple vaginal infection, which typically shows single organisms like E. coli or GBS without the polymicrobial anaerobic pattern. 1

Definitive Treatment Algorithm

For Simple, Low Fistulas:

Conservative surgical repair with local advancement flaps is the initial approach. 2

• Small fistulas with minimal symptoms may respond to conservative management over 3-6 months 2
• Endoscopic clip closure can be attempted for readily visualized, uncomplicated fistulas 3
• Local transperineal or transvaginal layered repair for accessible low fistulas 2, 4

For Complex or High Fistulas:

Surgical repair requires interposition of healthy, well-vascularized tissue between rectum and vagina. 2

Staged approach:

1. Initial diverting colostomy for severe symptoms or large fistulas to allow inflammation to resolve and relieve patient distress 2, 4
2. Allow 2-3 months for inflammation to subside before definitive repair 2
3. Definitive repair with tissue interposition (Martius flap, gracilis flap) for complex cases 2, 5
4. Transabdominal approach for high rectovaginal fistulas above the peritoneal reflection 2
5. Colostomy reversal 2-3 months after successful repair 4

Critical Pitfalls to Avoid

Do not attempt immediate repair in the presence of active inflammation or infection—this dramatically increases failure rates. 2

• Radiation-induced fistulas have extensive scarring and local ischemia, requiring more complex tissue interposition 2
• Concurrent anal sphincter damage must be repaired simultaneously with fistula closure 2
• Previous failed repairs significantly complicate subsequent attempts and may require more invasive procedures 2

Urgent Considerations

Approximately 11% of rectovaginal fistulas are caused by underlying malignancy—imaging must evaluate for soft tissue mass, wall thickening, or malignant lymphadenopathy. 6

Untreated fistulas can progress to sepsis, making early recognition and treatment crucial. 1