What is the recommended treatment for epithelialization of a laid open fistula tract?

Management of Epithelialization in Laid Open Fistula Tracts

Primary Concern and Recommendation

If a seton is left in place too long in a laid open fistula tract, epithelialization of the tract will occur and prevent spontaneous fistula closure, making this a critical timing consideration in perianal fistula management. 1

Understanding the Problem

Epithelialization represents a failure mode rather than a treatment goal in fistula management:

• When fistula tracts epithelialize, they transform into permanent epithelial-lined channels that will not close spontaneously 1
• This occurs when setons remain in place for extended periods without definitive intervention 1
• The epithelialized tract essentially becomes a "permanent fistula" requiring surgical intervention 1

Prevention Strategy (Most Important)

The key is preventing epithelialization through appropriate timing of seton removal:

• Remove setons after anti-TNF induction is completed (approximately 4 weeks) AND resolution of proctitis has been achieved 1
• Removing setons too early risks recurrent perianal abscess (15% rate when removed by Week 2) 1
• Leaving setons too long allows tract epithelialization and prevents closure 1

Management Once Epithelialization Has Occurred

For epithelialized tracts, definitive surgical intervention becomes necessary since spontaneous closure is no longer possible:

For Simple, Low Fistulas:

• Fistulotomy (laying open) achieves healing rates approaching 100% in carefully selected patients 2
• This involves laying open the primary tract, followed by debridement with or without marsupialization 1
• Appropriate only for subcutaneous, superficial, or low intersphincteric/trans-sphincteric fistulas in the lower third of sphincter 1

Critical Contraindications to Fistulotomy:

• Anterior fistulas in female patients (high incontinence risk due to short anterior sphincter) 1, 2
• Active proctitis (Crohn's Disease Activity Index >150) 1, 2
• Perineal Crohn's disease involvement 1
• Complex or high fistulas involving significant sphincter 1

For Complex or High Fistulas:

• Endorectal advancement flap closure (64% success rate in Crohn's patients, 80% in cryptoglandular) 1
• Requires absence of rectal stricture and controlled proctitis 1
• Concomitant immunosuppressive therapy advised for Crohn's-related fistulas 1

Special Considerations for Crohn's Disease

Medical therapy alone has limited efficacy once epithelialization occurs:

• Anti-TNF therapy shows only one-third achieving fistula healing in epithelialized tracts 3
• Complexity (multiple tracts) and associated stenosis further reduce healing rates 3
• If fistulae are associated with bowel stricture and/or abscess, surgery is strongly recommended 3

Common Pitfalls to Avoid

• Never use cutting setons - they cause 57% incontinence rates through forced sphincter transection 1
• Do not perform fistulotomy on anterior fistulas in females - asymmetrical anatomy guarantees incontinence 1
• Do not attempt fistulotomy with active proctitis - higher complication and recurrence rates 1, 2
• Do not delay definitive treatment indefinitely - prolonged seton placement leads to epithelialization 1

Optimal Management Algorithm

1. Assess fistula complexity and anatomy (imaging with MRI preferred) 3
2. Evaluate for active proctitis - must be medically controlled before surgery 1
3. Check for associated complications (abscess, stricture) - these require surgical management 3
4. For simple, low fistulas without contraindications: Fistulotomy with healing rates near 100% 2
5. For complex fistulas or those with contraindications: Advancement flap or other sphincter-preserving procedures 1
6. For refractory cases: Consider faecal diversion (reduces symptoms in two-thirds, but only one-fifth remain stoma-free long-term) 1