Treatment of Anorectal Fistula — Intersphincteric or Low Transsphincteric, Involving Less Than 30% of the External Anal Sphincter, with Normal Preoperative Continence
This protocol addresses management of patients with an intersphincteric or low transsphincteric anal fistula that involves less than 30% of the external anal sphincter and where preoperative sphincter function is intact — the defining features of a simple anal fistula.
Clinical Scenario
Simple anal fistulas are characterised as intersphincteric or low transsphincteric fistulas that involve less than 30% of the external anal sphincter (EAS) and carry no features of complexity. In this subgroup, involvement of the sphincter complex is minimal and preoperative continence is preserved — both are essential criteria that must be confirmed before selecting a treatment approach.
Treatment & Goals
Goal: Healing of the anal fistula
Management is based on a surgical approach targeting the fistula tract, chosen after thorough assessment of fistula anatomy, sphincter involvement, continence risk, and patient expectations; the protocol also specifies a supplementary wound care option and an alternative for patients who are not candidates for the primary procedure.
References
DOI: 10.1111/codi.1674
- 'Simple' anal fistulas include subcutaneous, intersphincteric or low transsphincteric fistulas with minimal involvement of the sphincter complex.
- Commonly used definitions of simple anal fistulas are intersphincteric or low transsphincteric fistulas that involve less than 30% of the EAS and do not have any features of complexity.
- Fistulotomy should be used in patients with intersphincteric or low transsphincteric anal fistula and normal preoperative continence, following a thorough assessment of fistula anatomy, symptomatology, involvement of sphincters, risk of incontinence and exploration of patient expectations.
- Marsupialization could be performed following fistulotomy and fistulectomy for simple anal fistula.
- Fistulotomy is thought to be the gold-standard treatment for simple anal fistula as it is associated with a high rate of fistula healing without diminishing continence.
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