What are the management options for an intersphincteric fistula in ano?

Management of Intersphincteric Fistula in Ano

For intersphincteric fistulas in ano, fistulotomy is the recommended treatment for subcutaneous or superficial tracts, while complex intersphincteric fistulas require loose seton placement followed by sphincter-sparing procedures such as LIFT (ligation of intersphincteric fistula tract) when medical therapy has optimized inflammation. 1

Initial Assessment and Drainage

Acute Presentation with Abscess

• If an intersphincteric abscess is present, immediate drainage into the rectal lumen through the internal opening is required, with consideration of limited internal sphincterotomy to facilitate drainage. 2
• Timing should be based on sepsis severity: emergent drainage for patients with sepsis, immunosuppression, diabetes, or diffuse cellulitis; otherwise within 24 hours. 1, 3
• Avoid probing for fistulas during acute abscess drainage to prevent iatrogenic tract creation. 1, 2, 3

Imaging Before Definitive Treatment

• MRI or endosonography is recommended before surgical intervention to define fistula anatomy and rule out occult sepsis, particularly for complex fistulas. 1
• This imaging helps identify the precise relationship of the tract to the sphincter complex, which is critical for surgical planning. 1

Definitive Surgical Management

Simple Intersphincteric Fistulas

• Fistulotomy by laying open the tract with debridement is recommended for subcutaneous, superficial, or intersphincteric fistulas in the lower third of the anal sphincter. 1
• This approach provides definitive treatment with minimal risk to continence when sphincter involvement is minimal. 1
• Contraindications include active proctitis or significant Crohn's disease activity. 1

Complex Intersphincteric Fistulas

• For fistulas involving significant sphincter muscle, place a loose draining seton initially to establish drainage and prevent abscess recurrence. 1, 3
• The seton should remain in place while medical therapy controls any associated inflammation. 1
• After inflammation is controlled (typically requiring concomitant medical therapy), proceed with sphincter-sparing procedures such as LIFT. 1, 4

Sphincter-Sparing Techniques

LIFT Procedure

• LIFT is the preferred sphincter-sparing technique for intersphincteric fistulas that cannot be safely laid open, with primary healing rates of 71-88% and no risk of incontinence. 5, 6, 7
• Long-term data demonstrates an 87.65% healing rate at median 71-month follow-up, with intersphincteric fistulas specifically showing 85.2% success. 7
• For patients with recurrence after initial LIFT, repeat LIFT or simple curettage achieves healing in the vast majority, with ultimate failure rates of less than 1%. 7
• LIFT is particularly effective for refractory fistulas, with 89% success at 3 months even in previously failed cases. 8

Alternative Sphincter-Sparing Options

• Other techniques mentioned in guidelines include advancement flap, fibrin glue, fistula plug, and VAAFT, though these have variable success rates (30-80%). 1, 8
• These should be considered secondary options when LIFT is not feasible or has failed. 1

Special Populations

Crohn's Disease

• Medical therapy to control disease-related inflammation is imperative before definitive surgical intervention. 1
• The most conservative approach should be adopted to avoid soft tissue damage and prevent extensive scarring. 1
• Maintenance therapy with thiopurines, infliximab, or adalimumab, combined with seton drainage, is recommended after surgery. 1
• Patients refractory to medical treatment should be considered for diverting ostomy, with proctectomy as last resort. 1

Critical Pitfalls to Avoid

• Never probe for fistulas during acute abscess drainage—this creates iatrogenic complications. 1, 2, 3
• Inadequate drainage and delayed time from disease onset to incision increase recurrence risk up to 44%. 2, 3
• Do not perform fistulotomy on intersphincteric fistulas involving significant sphincter muscle—use seton placement instead. 1, 3
• Avoid surgical treatment of concomitant perianal skin tags in Crohn's patients, as this leads to chronic non-healing ulcers. 1

Follow-Up and Recurrence Management

• Clinical assessment (decreased drainage) is usually sufficient for routine monitoring. 1
• MRI or endosonography combined with clinical assessment is recommended to evaluate fistula tract inflammation improvement. 1
• For recurrence after LIFT, options include repeat LIFT, fistulotomy if converted to simple intersphincteric tract, or curettage if no internal opening is found. 7