What is the optimal treatment plan for a middle-aged patient with internal fecal soiling, a normal sigmoidoscopy, a palpable rectal (PR) mucosal bulge on the left side, and a pelvic MRI showing a mass at the level of the levator ani with no external opening?

Optimal Treatment for Perianal Fistula at the Levator Ani Level

The LIFT (Ligation of Intersphincteric Fistula Tract) procedure is the optimal treatment for this patient with a trans-levator fistula without an external opening.

Diagnosis Assessment

Based on the clinical presentation and imaging findings, this patient has:

• Internal fecal soiling
• Normal sigmoidoscopy
• Left-sided mucosal bulge on digital rectal examination
• Posterior midline indentation
• MRI showing a mass at the levator ani level
• No external opening

These findings are consistent with a complex trans-levator fistula, likely of cryptoglandular origin, with the internal opening in the posterior midline and extension to the left side at the level of the levator ani muscle.

Treatment Rationale

Why LIFT is the Optimal Choice:

1. Anatomical Considerations:

   • The fistula involves the levator ani muscle, making it a complex trans-sphincteric or supra-sphincteric fistula 1
   • No external opening is present, which makes seton placement challenging and glue sealing less effective
   • MRI has accurately identified the fistula tract in relation to the sphincter complex 2

2. Evidence-Based Approach:

   • MRI is the gold standard for preoperative assessment of anal fistulas, with high sensitivity and specificity for delineating fistula anatomy 1, 2
   • For complex fistulas involving the levator ani, sphincter-preserving procedures are preferred to minimize risk of incontinence
   • LIFT provides access to the intersphincteric plane where the fistula can be identified, ligated, and divided 3

3. Advantages Over Other Options:

   • Seton (Option A): Requires both internal and external openings for placement; this patient lacks an external opening
   • Lay open from inside (Option B): High risk of incontinence for trans-levator fistulas due to division of significant sphincter muscle
   • Glue sealing (Option C): Less effective for complex fistulas without external drainage and has high failure rates in complex tracks 1

Procedural Approach

1. Preoperative Planning:

   • Complete review of MRI to identify the exact course of the fistula tract through the levator ani 3
   • Assessment of internal opening location (posterior midline based on examination)
   • Evaluation of the left-sided extension at the levator ani level

2. LIFT Procedure Steps:

   • Create an incision in the intersphincteric groove
   • Identify the fistula tract as it crosses the intersphincteric plane
   • Ligate the tract close to the internal opening
   • Divide the tract between ligatures
   • Curette the remaining tract toward the levator ani
   • Close the defect at the internal sphincter side

Important Considerations

• Preoperative MRI Contribution: MRI significantly improves surgical planning for complex fistulas, particularly when the external opening is absent or distant from the anal canal (>2 cm) 2

• Potential Complications:

  • Recurrence (10-40%)
  • Persistent drainage
  • Wound healing issues

• Follow-up Protocol:

  • Clinical examination at 2 weeks, 6 weeks, and 3 months
  • Repeat MRI if symptoms recur to assess for persistent or recurrent fistula

Common Pitfalls to Avoid

1. Inadequate Preoperative Imaging: Relying solely on clinical examination can miss secondary tracts or extensions 2

2. Misidentification of Internal Opening: The internal opening is likely in the posterior midline based on the indentation noted on examination

3. Underestimating Complexity: Trans-levator fistulas require specialized approaches; simple fistulotomy would lead to high risk of incontinence

4. Incomplete Treatment: Failure to address all components of the fistula tract can lead to recurrence

The LIFT procedure offers the best balance of efficacy and sphincter preservation for this complex trans-levator fistula without an external opening, making it the optimal treatment choice for this patient.