title: Predictors of outcome after transanal advancement flap repair for high transsphincteric fistulas.
abstract: BACKGROUND
  Transanal advancement flap repair fails in 1 of every 3 patients with a high transsphincteric fistula. It has been reported that smoking, obesity, and previous attempts at repair adversely affect the outcome of transanal advancement flap repair. Because these findings could not be confirmed by other studies, it is still unclear whether these and other factors have an impact on the outcome.
  
  
  OBJECTIVE
  The aim of this study was to identify predictors of outcome in a large cohort of patients who underwent transanal advancement flap repair for a high transsphincteric fistula.
  
  
  METHODS
  This study was performed as a retrospective review.
  
  
  METHODS
  The study was conducted at the Division of Colon and Rectal Surgery, Erasmus MC, between 2000 and 2012.
  
  
  METHODS
  A consecutive series of 252 patients with a high transsphincteric fistula of cryptoglandular origin were included. Patients with a rectovaginal or Crohn fistula were excluded.
  
  
  METHODS
  All patients underwent transanal advancement flap repair. Preoperatively, patients underwent endoanal MRI.
  
  
  METHODS
  Healing was defined as complete wound healing with absence of symptoms. Patients were followed up to assess failure. Seventeen patient- and fistula-related variables were assessed.
  
  
  RESULTS
  Median duration of follow-up was 21 months (range, 6-136 months). The failure rate at 3 years was 41% (95% CI, 34-48). None of the studied variables predicted the outcome of flap repair except horseshoe extension. In univariate and multivariate analyses, significantly less failures were observed in patients with a horseshoe extension (p < 0.05).
  
  
  CONCLUSIONS
  Retrospective design, a single surgeon series, and potential selection bias caused by the tertiary referral center status are the limitations of this study.
  
  
  CONCLUSIONS
  Of all studied variables, horseshoe extension was found to be the only positive predictor of outcome after flap repair for high transsphincteric fistulas.
authors.affiliation: 1Department of Surgery, Erasmus MC, University Medical Center, Rotterdam, the Netherlands 2Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands 3Department of Surgery, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Robbert S
authors.initials: RS
authors.lastname: van Onkelen
authors.forename: Martijn P
authors.initials: MP
authors.lastname: Gosselink
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Thijsse
authors.forename: Willem R
authors.initials: WR
authors.lastname: Schouten
mesh_terms: D000328:Adult; D001003:Anal Canal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012003:Rectal Fistula / Q000601:surgery*; D012189:Retrospective Studies; D013524:Surgical Flaps; D016896:Treatment Outcome; D014945:Wound Healing