Rectal advancement flap for the treatment of complex cryptoglandular anal fistulas: a systematic review and meta-analysis

Rectal advancement flap is an accepted approach for treating complex fistula-in-ano. However, a diversity of technical modifications have been described. The aim of this study was to evaluate recurrence and fecal continence rates after performing rectal advancement flaps depending upon flap thickness (full-thickness, partial-thickness, or mucosal flaps) and treatment of the fistulous tract (core-out or curettage). Medline (PubMed, Ovid), the Cochrane Library database, and ClinicalTrials.gov were searched. Studies that involved patients with complex cryptoglandular fistulas who had been treated with rectal advancement flaps were included. The outcomes measured were recurrence and fecal continence. All of the statistical analyses were performed using Comprehensive Meta-Analysis software. A fixed model was used if there was no evidence of heterogeneity; otherwise, a random effects model was used. Twenty-six studies were included (1655 patients). The pooled rate of recurrence was 21%. Full-thickness flaps showed the best results concerning recurrence (7.4%), partial flaps revealed 19% and mucosal flaps 30.1%. Core-out and curettage had a similar recurrence (19 vs 21%). Regarding anal incontinence, the pooled rate was 13.3%. Mucosal- and partial-thickness flaps showed similar rates (9.3 vs 10.2%), while full-thickness flaps disturbed it in 20.4%. Most of these alterations were minor symptoms. Otherwise, core-out and curettage showed similar rates (14.3 vs 12%). 1. Full-thickness rectal advancement flaps offer better results regarding the recurrence than mucosal or partial flaps. 2. All flaps cause some incontinence, which increases with the thickness of the flap. 3. The results did not suggest differences in recurrence and incontinence between core-out and curettage.