What is the recommended treatment for a simple fistula-in-ano?

Management of Simple Fistula-in-Ano: Fistulotomy as First-Line Treatment

For simple fistula-in-ano, fistulotomy is the recommended first-line surgical treatment with healing rates exceeding 90% and should be performed when the fistula tract does not involve significant sphincter muscle. 1

Classification and Diagnosis

Simple fistula-in-ano is characterized by:

• Low tract (superficial, intersphincteric, or low transsphincteric)
• Single external opening
• No evidence of rectovaginal involvement
• No evidence of inflammatory bowel disease
• No history of radiation
• No pre-existing incontinence

Before proceeding with treatment:

• Ensure proper diagnosis with examination under anesthesia (EUA) to confirm fistula type
• Rule out perianal abscess which must be drained first
• Consider imaging (MRI or endoanal ultrasound) if anatomy is unclear

Treatment Algorithm

First-Line Treatment: Fistulotomy

• Indicated for simple fistulas with minimal or no sphincter involvement 1, 2
• Procedure involves laying open the fistula tract
• Healing rates >93% with low recurrence rates 2, 3
• Shorter operating time (approximately 22 minutes vs. 31 minutes for fistulectomy) 2
• Shorter hospital stay and faster wound healing compared to fistulectomy 2

Key Considerations for Fistulotomy

• Before proceeding: Rule out Crohn's disease or other inflammatory bowel disease
• Technique: Complete unroofing of the tract from external to internal opening
• Post-procedure care: Regular wound cleaning with warm water or saline 2-3 times daily 4
• Follow-up: First visit within 48-72 hours, then every 1-2 weeks until complete healing 4

When to Avoid Fistulotomy

• Complex fistulas with significant sphincter involvement
• Patients with pre-existing incontinence
• Patients with Crohn's disease (use seton placement instead) 1
• Women with anterior fistulas (higher risk of incontinence)
• Elderly patients with compromised sphincter function

Alternative Treatments

For Simple Fistulas When Fistulotomy Is Contraindicated

1. Seton placement: Temporary drainage to control infection 1
2. Fibrin glue: Non-invasive option with 85% success rate in selected cases 5
3. External sphincter-sparing anal fistulotomy (ESSAF): Modified technique with 71% primary healing rate 6

For Complex Fistulas (Not Recommended for Simple Fistulas)

• LIFT procedure (Ligation of Intersphincteric Fistula Tract)
• Endorectal advancement flap
• Video-assisted anal fistula treatment (VAAFT)

Potential Complications and Management

Incontinence Risk

• Overall incontinence risk with fistulotomy for simple fistulas: approximately 12.7% 3
• Minor incontinence (gas, soiling) more common than major incontinence
• Risk factors: female gender, anterior fistulas, previous anorectal surgery

Recurrence

• Recurrence rate after fistulotomy: approximately 6-8%
• Higher recurrence rates with sphincter-sparing techniques (up to 22%)
• Management of recurrence may require repeat procedure or alternative approach

Special Considerations

Antibiotics

• Not routinely indicated after uncomplicated fistulotomy
• Consider in cases of surrounding cellulitis, immunocompromised patients, or systemic signs of infection 1

Follow-up Protocol

• Assess wound healing at each visit
• Monitor for signs of recurrence or persistent drainage
• Evaluate continence status

Conclusion

Fistulotomy remains the gold standard treatment for simple fistula-in-ano with minimal sphincter involvement, offering the highest healing rates and acceptable functional outcomes. Alternative sphincter-sparing techniques should be considered for patients with risk factors for incontinence or complex fistulas.