Can an advancement rectal flap (ARF) be considered as the first surgical intervention for complex anal fistulas?

Advancement Rectal Flap as First Surgical Intervention for Complex Fistula

No, advancement rectal flap should NOT be the first surgical intervention for complex anal fistulas—seton drainage must be performed first to control sepsis and allow inflammation to subside. 1, 2

Initial Mandatory Step: Drainage and Seton Placement

Before any definitive surgical repair, including advancement flap, sepsis must be drained using loose setons. 1 This is non-negotiable for complex fistulas:

• Examination under anesthesia (EUA) with abscess drainage and loose seton placement is the mandatory initial step for complex perianal fistulas. 2, 3
• Seton placement prevents recurrence of abscesses, allows inflammation around the tract to subside, and facilitates personal hygiene. 1
• The fistula tract running through the sphincter complex must be identified and provided with a seton to prevent development of more complex fistula. 1

Why Advancement Flap is a Second-Stage Procedure

The ECCO-ESCP consensus explicitly states that rectal advancement flap is "typically described as a second stage for high fistulae." 1 The reasoning is clear:

• Advancement flaps require a clean, non-inflamed surgical field for optimal healing. 1
• Poor wound healing occurs mainly in patients with active inflammation in the rectum. 1
• Success rates drop significantly when performed in the presence of active disease (64% for Crohn's fistulas vs 80% for cryptoglandular fistulas). 1

Specific Contraindications to Immediate Advancement Flap

Do not perform advancement flap as first intervention if any of the following are present:

• Moderate to severe proctitis—seton placement is the only sensible option. 1
• Active inflammation of the rectosigmoid colon. 1, 2
• Presence of undrained abscess or active sepsis. 1, 2, 3
• Rectal stricture. 1

The Correct Algorithmic Approach

For complex anal fistulas, follow this sequence:

1. Obtain pelvic MRI with contrast before surgical intervention to define anatomy and identify occult abscesses. 2, 3
2. Perform EUA with drainage of any abscess and loose seton placement. 2, 3
3. Initiate medical therapy (antibiotics for simple fistulas; anti-TNF therapy combined with immunomodulators for complex fistulas). 2, 3
4. Wait for inflammation to subside (setons may remain in place for 6-8 weeks or longer, with removal at median of 33 weeks when combined with optimal medical therapy). 1
5. Perform proctosigmoidoscopy to confirm absence of active rectosigmoid inflammation. 1, 2, 3
6. Only then consider advancement flap as definitive repair for high fistulae unsuitable for fistulotomy. 1

When Advancement Flap is Appropriate (After Seton Drainage)

Advancement flap is the most common and successful procedure for:

• High trans-sphincteric fistulas (upper two-thirds of sphincter complex) where fistulotomy would compromise continence. 1
• Crohn's-related rectovaginal fistulae (provided sphincter complex is intact and rectosigmoid mucosa has healed). 1
• Complex cryptoglandular fistulas after seton drainage. 1

Critical Pitfalls to Avoid

Never attempt advancement flap without prior seton drainage in complex fistulas—this violates fundamental surgical principles and increases failure risk. 1

• Medical therapy without surgical drainage is contraindicated in the presence of abscess or complex fistula. 3
• Surgical repair can only be performed when there is endoscopic healing of the rectosigmoid mucosa. 1
• Cigarette smoking significantly impacts flap repair results negatively—counsel patients on cessation. 1
• Active Crohn's disease in the rectum substantially reduces healing rates (64% vs 80% for cryptoglandular). 1

Expected Outcomes When Properly Staged

When advancement flap is performed as a second-stage procedure after appropriate seton drainage:

• Primary healing rates of 69-81% for complex fistulas. 4, 5, 6
• Overall healing rates of 93% when including repeat flap procedures. 5
• Minimal impact on continence when properly executed. 4, 5, 7
• Repeat advancement flap is feasible and effective (78% success) if initial flap fails. 8