Horseshoe tract of anal fistula: bad luck or an avoidable extension? Lessons from 82 cases

AIM: The aim of this study was to analyse the characteristics of horseshoe tract formation in anal fistula. METHOD: We retrospectively analysed the data from all consecutive patients who underwent surgery for an anal fistula from November 2004 to March 2011. A horseshoe tract was defined as a circumferential extension connecting both sides of the anorectum. RESULTS: During the period of analysis, 1876 patients were operated on for a fistula. Of these, 82 (4.4%) had a horseshoe extension. The majority (72%) were male and the median age was 46 (17-84) years. The primary tract was high transsphincteric in 90% of cases and the primary opening was posterior in 65% of cases. The location of the horseshoe extension was posterior in 66% of cases with spread in the deep perianal space in 62%. In all, 71% were cryptoglandular and 24% were seen in Crohn's disease (20). Of the 62 non-Crohn's patients previous treatment was common and included surgery (42), antibiotics alone (41) and non-steroidal anti-inflammatory drugs (21). CONCLUSION: Horseshoe extension in anal fistula is uncommon. With Crohn's disease excepted, the majority had had previous treatment.