Faecal incontinence after seton treatment for anal fistulae with and without surgical division of internal anal sphincter: a systematic review.

OBJECTIVE: The challenge of surgery for anal fistula is to eradicate the fistula track while maintaining anal continence. Seton placement is recommended to reduce postoperative faecal incontinence but interestingly a great range of functional impairment after surgery has been published. The aim of this study was to analyse the influence of intra-operative internal anal sphincter division during tight or cutting seton technique for cryptogenic anal fistula, on the results of recurrence and postoperative faecal incontinence.
METHOD: A systematic literature review was performed to identify published series from 1966 to May 2007 of patients with anal fistula treated by a tight or cutting seton technique. The published series has been divided in to those where preservation of internal anal sphincter was performed (PIAS group) or where intra-operative surgical division was undertaken in the time of seton placement (SIAS group) .The main endpoints of the review were to study anal fistula recurrence rate and postoperative faecal incontinence.
RESULTS: Eighteen studies including 19 series and 448 patients were analysed in detail. Recurrence rate was 5.0% and 3.0% in PIAS and SIAS group respectively. Overall faecal incontinence rate was 5.6% in PIAS group and 25.2% in SIAS group.
CONCLUSION: Although based on low-evidence studies, intra-operative preservation of internal anal sphincter at the time of seton insertion for anal fistula seems to reduce the postoperative faecal incontinence without a substantial increase in recurrence rates.