What are the surgical management options for perianal fistulas?

Surgical Management Options for Perianal Fistulas

The optimal surgical management of perianal fistulas requires a combination of appropriate drainage procedures and definitive treatments based on fistula classification, with seton placement being the cornerstone therapy for complex fistulas. 1

Initial Assessment and Classification

Before any surgical intervention, proper assessment is crucial:

• Imaging: Contrast-enhanced pelvic MRI is the first-line imaging modality for perianal fistulas with 97% sensitivity for discriminating complex from simple disease 1, 2
• Examination Under Anesthesia (EUA): Considered the gold standard when performed by an experienced surgeon 1
• Proctosigmoidoscopy: Essential to assess for rectal inflammation which significantly impacts treatment outcomes 1

Fistulas are generally classified as:

• Simple: Low, superficial fistulas with single tract
• Complex: High fistulas, multiple tracts, rectovaginal fistulas, or those with associated abscess 1

Surgical Management Algorithm

1. Management of Associated Abscess

• Immediate drainage of any perianal abscess is mandatory before definitive fistula treatment 1, 3
• More than two-thirds of patients with fistulas have associated abscesses that must be drained 1

2. Simple Fistulas

• Fistulotomy: Can be considered for uncomplicated low anal fistulas 1
• Seton placement + antibiotics: Preferred initial strategy for symptomatic simple fistulas 1
  • Antibiotics typically include metronidazole and/or ciprofloxacin

3. Complex Fistulas

• Seton placement: Recommended after surgical treatment of sepsis 1
  • Timing of removal depends on subsequent therapy
  • Improves rates of healing and reduces recurrence when placed prior to anti-TNF therapy 1

4. Advanced Surgical Options

For selected patients with persistent fistulas despite initial management:

• Mucosal advancement flap: Effective in selected patients, with healing in approximately two-thirds at 1 year, but progressive failure over time 1
• Ligation of intersphincteric fistula tract (LIFT): Similar efficacy profile to advancement flaps 1
• Fistula plug: May be effective in about 55% of Crohn's disease-related fistulae 1
• Fibrin glue: Shown to achieve remission in 38% of patients after 8 weeks (vs 16% with observation only) 1
• Video-assisted anal fistula treatment (VAAFT): When combined with advancement flap, reported 82% success rate at 9 months 1

5. Refractory Disease

For patients who fail medical and surgical treatments:

• Fecal stream diversion (temporary ostomy): For severe refractory perianal disease 1
• Proctectomy: Last resort for severe, treatment-resistant disease 1

Special Considerations

Crohn's Disease-Related Fistulas

• Active luminal Crohn's disease should be treated concurrently with appropriate medical therapy 1
• Infliximab should be started as first-line biological therapy for complex perianal fistulae once adequate drainage of sepsis is achieved 1
• Combined medical-surgical approach yields better outcomes than either approach alone 1, 4

Newer Therapies

• Allogeneic adipose-derived stem cells (darvadstrocel): Complete remission rate of 50% at 24 weeks and 56.3% at 1 year in treatment-refractory complex fistulas 1

Important Caveats

• Long-term outcomes of surgical interventions for complex perianal fistulas are generally poor, with persistent fistulas in 58% of patients despite combined medical-surgical management 4
• Patients should be counseled that advanced surgical options have limited long-term success, particularly with complex disease and ongoing inflammation 1
• Concomitant perianal skin tags should not be treated surgically as this can lead to chronic, non-healing ulcers 1
• The presence of rectal inflammation significantly reduces healing rates and may necessitate more aggressive medical therapy before definitive surgical repair 1

The surgical management of perianal fistulas requires a stepwise approach based on fistula complexity, with appropriate drainage of sepsis as the first step, followed by seton placement and consideration of more advanced techniques in selected cases.