Treatment for Intersphincteric Fistula
For a low-lying intersphincteric anal fistula, perform a fistulotomy (laying open the tract) as the definitive treatment, which is simple, effective, and provides excellent healing rates with minimal risk of incontinence in this specific fistula type.
Surgical Approach
The treatment strategy for intersphincteric fistulas depends on whether you're dealing with an acute presentation (with abscess) or a chronic fistula:
Acute Setting (Fistula with Abscess)
If you encounter an intersphincteric fistula during drainage of an anorectal abscess:
- Perform immediate fistulotomy if the fistula is low and subcutaneous (not involving sphincter muscle) 1
- Place a loose draining seton if any sphincter muscle is involved 1
- Do not probe for occult fistulas during abscess drainage to avoid iatrogenic tract creation 1
Elective Setting (Chronic Fistula)
For established low intersphincteric fistulas without active infection:
Primary treatment: Fistulotomy (lay-open technique)
- This involves laying open the entire fistula tract and trimming redundant tissue for adequate drainage 2, 3, 4
- Only the internal sphincter is divided in true intersphincteric fistulas
- This provides definitive cure with low recurrence rates
Important Caveats and Patient Selection
High-Risk Patients for Incontinence
Be more conservative with fistulotomy in patients with:
- Low preoperative resting anal pressure (the only independent predictor of postoperative incontinence) 3
- Female patients (higher risk of continence issues) 3
- Pre-existing sphincter weakness
In these high-risk patients, consider sphincter-preserving alternatives such as:
- LIFT procedure (Ligation of Intersphincteric Fistula Tract): Recent high-quality evidence shows LIFT offers significantly lower postoperative pain, faster wound healing (93.3% vs 53.3%), fewer wound infections (6.7% vs 46.7%), and shorter hospital stays compared to conventional fistulotomy 5, 6
- The LIFT technique is particularly valuable when sphincter preservation is paramount
Expected Functional Outcomes
After standard fistulotomy for intersphincteric fistulas 3:
- Expect significant decrease in maximal resting anal pressure
- Squeeze pressure typically remains preserved
- Most patients maintain satisfactory continence unless they have the risk factors mentioned above
Common Pitfalls to Avoid
Don't confuse low transsphincteric with intersphincteric fistulas: True intersphincteric fistulas track between the internal and external sphincter layers without penetrating the external sphincter. Low transsphincteric fistulas penetrate the lower external sphincter and may require different management 7
Don't perform fistulotomy for high or complex fistulas: These require staged procedures with seton placement to prevent incontinence 4
Assess sphincter function preoperatively: Check for baseline continence issues and consider manometry in borderline cases 3
Consider imaging if anatomy is unclear: MRI or endoanal ultrasound can clarify the fistula tract course and identify unexpected complexity 1, 8