Fistulectomy Layout and Procedure
Fistulectomy (laying open the fistula tract) should only be performed for low, subcutaneous fistulas that do not involve the sphincter muscle; for any fistula involving sphincter muscle, place a loose draining seton instead to avoid incontinence. 1
Patient Selection and Contraindications
Appropriate Candidates for Fistulectomy
- Low/subcutaneous fistulas not involving any sphincter muscle can be laid open at the time of abscess drainage 1, 2
- Intersphincteric or low trans-sphincteric single tract fistulas in the lower third of the anal sphincter may be considered in highly selected cases 1
- Patients must have no active abscess present 2
- In Crohn's disease patients, the Crohn's Disease Activity Index (CDAI) must be <150 1, 2
Absolute Contraindications
- Any fistula involving sphincter muscle - these require seton placement, not fistulotomy 1, 2
- Anterior fistulas in female patients - the asymmetrical anatomy and short anterior sphincter make fistulotomy highly likely to cause incontinence 1
- Active proctitis in Crohn's disease - dramatically reduces healing rates 2
- Active abscess present - must drain first with loose seton 2
- Evidence of perineal Crohn's disease involvement 2
Surgical Technique
Standard Fistulotomy Procedure
- Identify the primary tract and any secondary extensions through careful examination under anesthesia 1
- Lay open the entire fistula tract from internal to external opening 1
- Debride the tract thoroughly, with or without marsupialization 1
- Keep the incision as close as possible to the anal verge to minimize the length of any potential future fistula 3
- Do not probe or use hydrogen peroxide to search for fistulas if not obvious, as this causes iatrogenic complications 1
Advanced Technique: Fistulectomy with Primary Sphincter Reconstruction
For complex fistulas where sphincter division is necessary, immediate sphincter reconstruction can be performed 4, 5, 6:
- This technique achieves 84-96% healing rates with acceptable continence outcomes 4, 5, 6
- High trans-sphincteric fistulas show 4-fold increased risk of incontinence compared to non-high tracts 4
- Male sex and recurrent fistulas may have protective effects against postoperative incontinence 4
- Preoperative continence disorders improve significantly (mean Wexner score decreased from 7.2 to 2.0, p=0.008) 5
Critical Pitfalls and Risk Factors
Incontinence Risk
- Cutting setons are strongly disadvised - associated with 57% incontinence rate due to forced sphincter migration 1
- Overall fistulotomy carries approximately 20% risk of continence deterioration, mostly minor 7
- Secondary extensions are associated with failure to achieve cure (p=0.008) 7
- Longer time to referral correlates with worse final continence outcomes 7
Recurrence Risk Factors
- Inadequate drainage at initial procedure 3
- Loculations and horseshoe-type abscesses 3
- Delayed time from disease onset to incision 3
- Risk of recurrence after drainage alone can reach 44% 3
Special Considerations for Crohn's Disease
Medical Optimization Required
- Control luminal Crohn's disease with thiopurines, infliximab, or adalimumab before and after surgery 2
- Assess the rectum for proctitis at time of any drainage procedure 2
- Seton removal timing: wait until anti-TNF induction phase is completed (approximately 1 month) and proctitis has resolved 1
Alternative Approaches for Complex Crohn's Fistulas
- Loose setons may be definitive treatment when combined with optimal medical therapy, with seton removal in up to 98% at median 33 weeks 1
- Endorectal advancement flap for high fistulas unsuitable for fistulotomy, with 64% weighted success rate in Crohn's patients 1
- Diverting ostomy for refractory cases, though only one-fifth remain stoma-free long-term 1, 2
Postoperative Management
Wound Care
- Avoid wound packing - it is costly, painful, and provides no benefit to healing 1
- Monitor for adequate drainage and signs of recurrence 3