Fistulotomy for Simple Anal Fistula
For an adult patient with a simple, low anal fistula and no significant comorbidities, fistulotomy is the definitive treatment of choice, achieving healing rates approaching 100%. 1
Indications for Fistulotomy
Fistulotomy should be performed in carefully selected patients meeting ALL of the following criteria:
- Simple, low intersphincteric or low transsphincteric fistula involving only the lower third of the external sphincter 2, 1
- Absence of active proctitis or rectosigmoid inflammation - this is an absolute contraindication 2, 1
- Single, non-branching fistula tract without complex anatomy 1
- No evidence of Crohn's disease (CDAI <150 if Crohn's suspected) 1
- Not an anterior fistula in a female patient - this is an absolute contraindication due to the short anterior sphincter and high incontinence risk 2, 1
Pre-Operative Assessment
Essential evaluation includes:
- Examination under anesthesia (EUA) to accurately define fistula anatomy and rule out occult abscess 1
- Proctosigmoidoscopy to evaluate for concomitant rectal inflammation, which critically affects treatment decisions 1
- MRI or endoanal ultrasound if anatomy is unclear or complex features suspected 1
Surgical Technique
The procedure involves:
- Laying open the primary fistula tract and any side branches completely 1
- Keeping the incision as close as possible to the anal verge to minimize potential fistula length 3
- Marsupializing the wound edges to improve healing 2
Expected Outcomes
Fistulotomy provides excellent results in appropriately selected patients:
- Healing rate: 93.7-100% in simple fistulas 1, 4, 5
- Recurrence rate: <5% with proper technique 4, 5
- Risk of continence impairment: 12.7% overall, though mostly minor (gas/urge incontinence) 4, 6
Critical Contraindications - Never Perform Fistulotomy If:
The following are absolute contraindications:
- Active proctitis or inflammatory bowel disease with active inflammation 2, 1
- Anterior fistula in female patients - high risk of keyhole deformity and incontinence 2, 1
- Complex, high transsphincteric or suprasphincteric fistulas involving significant sphincter muscle 2, 1
- Evidence of perineal Crohn's disease involvement 1
- Compromised baseline continence or previous sphincter injury 7
Alternative Management When Fistulotomy is Contraindicated
For fistulas involving significant sphincter muscle:
- Place a loose, non-cutting draining seton as primary treatment to establish drainage 2, 1, 3
- Never use cutting setons - they result in incontinence rates up to 57% and keyhole deformity 2, 1
- Consider sphincter-preserving techniques after inflammation resolves: LIFT procedure (77% success in cryptoglandular fistulas) or advancement flap (61-80% success) 2, 1
Management of Concomitant Abscess
If abscess is present with fistula:
- Drain the abscess first - more than two-thirds of fistula patients have an associated abscess 1
- Perform immediate fistulotomy only for subcutaneous fistulas not involving sphincter muscle 2
- Place loose seton for any sphincter involvement rather than attempting definitive fistulotomy in the acute setting 2, 3
Post-Operative Considerations
To optimize continence recovery:
- Kegel exercises (50 repetitions daily for one year) can significantly improve post-fistulotomy gas and urge incontinence, restoring continence to near-baseline levels 6
- Stool softeners and high-fiber diet to prevent straining 8
- Sitz baths 2-3 times daily for wound care 8
Common Pitfalls to Avoid
Critical errors that compromise outcomes:
- Probing aggressively for fistula tracts during initial examination creates iatrogenic complexity 2, 1
- Performing fistulotomy in the presence of proctitis leads to poor healing and high recurrence 2, 1
- Inadequate drainage of the entire tract including side branches increases recurrence risk 3
- Dividing sphincter muscle unnecessarily in patients who could be managed with sphincter-preserving techniques 9, 4