Complex anal fistulas that traverse or involve a significant portion of the sphincter complex present a distinct surgical challenge — standard fistulotomy carries an unacceptable risk of sphincter damage in these cases. This protocol addresses the structured evidence-based approach for this specific population.
This protocol applies to patients with any of the following:
These features define complex anal fistula — a category where sphincter preservation is the central therapeutic priority.
Definitive management centres on sphincter-preserving surgical techniques — the specific procedure and its indications depend on individual fistula characteristics and patient factors detailed in the full protocol.
DOI: 10.1111/codi.1674
'Complex' anal fistulas are extrasphincteric, suprasphincteric or high transsphincteric fistulas involving greater than 30% of the external anal sphincter (EAS) and intersphincteric fistulas involving greater than 50% of the IAS.
Rectovaginal fistula, anterior fistula in women, recurrent fistula and fistulas with horseshoe or multiple extensions are also classified as complex fistulas.
LIFT should be used in the primary treatment of new, high transsphincteric fistulas.
Advancement flap should be used for the management of high anal fistula.
Advancement flap has a high rate of fistula healing and is associated with minor incontinence which increased in severity with increases in flap thickness.