What is the initial management for patients presenting with fistulas?

Initial Management of Fistulas

The initial management of patients presenting with fistulas should focus on controlling sepsis through antibiotics and drainage of any associated abscesses, followed by appropriate medical or surgical interventions based on fistula type and location. 1

Assessment and Classification

• Accurate diagnosis and classification are essential first steps in fistula management, requiring imaging studies and often examination under anesthesia (EUA) 2
• Contrast-enhanced pelvic MRI is the recommended initial imaging procedure for perianal fistulas, with endoscopic anorectal ultrasound as an alternative 2
• Proctosigmoidoscopy should be performed to assess for concomitant rectosigmoid inflammation, which affects treatment decisions 2
• Fistulas should be classified by type (perianal, enterocutaneous, enterovaginal, enterovesical, enteroenteric) and complexity (simple vs. complex) 1, 3

Initial Management by Fistula Type

Perianal Fistulas

• For acute perianal abscesses: Adequate surgical drainage under general anesthesia is the first step, with no routine requirement for wound packing 1
• Important: No active attempt should be made to find an associated fistula during initial abscess drainage, as this may create iatrogenic tracks 1, 4
• If an obvious fistula exists, a loose draining seton (soft material) should be inserted without attempting to lay the fistula open 1
• First-line medical treatment includes antibiotics (metronidazole 400 mg three times daily and/or ciprofloxacin 500 mg twice daily) 2
• For complex perianal fistulas, imaging before surgical drainage is strongly recommended 2

Enterocutaneous Fistulas

• Initial management includes control of sepsis, correction of fluid and electrolyte imbalances, nutritional support, and proper wound care 5
• Low-volume enterocutaneous fistulas may be controlled with immunomodulator and biological therapy 1
• High-volume fistulas usually require surgical intervention to achieve symptom control 1, 5
• Patients with nutritional deficiencies and high-output fistulas require nutritional and biochemical optimization before definitive management 1

Enterovaginal and Enterovesical Fistulas

• These should be managed jointly with medical control of inflammation and surgical resection 1
• Initial medical therapy is recommended, with surgery reserved for those with bowel obstruction, abscess formation, or who fail medical therapy 1, 6
• For rectovaginal fistulas, closure at week 14 after infliximab induction therapy can be achieved in approximately 45% of cases 1

Enteroenteric Fistulas

• Often asymptomatic and may not always require surgical intervention 1
• Management decisions should be based on symptoms and complications 1

Management of Associated Abscesses

• Intra-abdominal abscesses should be treated initially with intravenous antibiotics and, where possible, radiological drainage 1
• Surgical drainage may be required, but immediate resection should be avoided 1
• Critical: Anti-TNF therapy should only be started after abscesses have been treated with antibiotics and, where possible, drainage 1

Medical Therapy Options

• For fistulas associated with active inflammation, medical therapy with immunosuppressants is worthwhile 1
• Anti-TNF therapy (particularly infliximab) has shown efficacy for fistulizing Crohn's disease 1, 2
• For simple fistulas not responding to antibiotics, thiopurines (azathioprine or mercaptopurine) can be used as second-line therapy 2
• For complex fistulas, anti-TNF therapy combined with immunomodulators is recommended after surgical drainage 2

Nutritional Considerations

• Patients with CD and distal (low ileal or colonic) fistula with low output can usually receive nutritional support via the enteral route 1
• Patients with proximal fistula and/or very high output should receive nutritional support by partial or exclusive parenteral nutrition 1
• Adequate hydration is essential to prevent complications like venous thromboembolism 1

Monitoring Response

• Clinical assessment (decreased drainage) combined with MRI or anal endosonography is recommended to evaluate improvement 2
• Be aware that clinical closure does not always equal MRI closure, with high risk of recurrence without complete fibrotic tract on MRI 2

Special Considerations

• All patients with enterocutaneous fistulae should be managed by a multidisciplinary team due to the complexity of care required 1
• Following treatment of an abdominal abscess in non-perianal fistulizing Crohn's disease, joint medical and surgical discussion is required, but interval surgical resection is not always necessary 1
• For aortoenteric fistulas (rare but life-threatening), emergency intervention with either open surgical reconstruction or endovascular therapy is required 1