Is the Outcome of Transanal Advancement Flap Repair Affected by the Complexity of High Transsphincteric Fistulas?

Abstract

Transanal advancement flap repair for the treatment of high transsphincteric fistulas fails in 1 of every 3 patients. Until now no definite risk factors for failure have been identified. The question is whether the more complex fistulas, such as those with horseshoe extensions and associated abscesses, have a less favorable outcome. Aim of the present study was to indentify whether more complex fistulas have a less favorable outcome. This study is a retrospective case series review. Between 1995 and 2007 a series of 162 patients underwent endoanal MR imaging before transanal advancement flap repair. Two investigators, without prior knowledge of the surgical findings, reviewed all MR images. Lateral fistulas were identified in 5 patients. Because of the small number, these patients were excluded from further analysis. Posterior fistulas were identified in 119 patients (76%). These fistulas had 3 types of extensions: a direct course (36%), a classic horseshoe extension (23%), or an intersphincteric horseshoe extension (41%). The corresponding healing rates were 37%, 81%, and 73%. Anterior fistulas were observed in 23% of the patients. These fistulas had 2 types of extensions: a direct course (61%) or a classic horseshoe extension (39%). The corresponding healing rates were 60% and 52%. The healing rate of fistulas with a direct course was significantly lower than the healing rate of fistulas with a classic or intersphincteric horseshoe extension. Associated abscesses were found in 47% of the posterior fistulas and 5% of the anterior fistulas. Once adequately drained, these abscesses did not affect the outcome of transanal advancement flap repair. The complexity of high transsphincteric fistulas does not affect the outcome of transanal advancement flap repair.