Randomized clinical trial of local gentamicin-collagen treatment in advancement flap repair for anal fistula

Background: Endoanal advancement flap repair is widely used in sphincter-preserving surgery for anal fistula, but the high recurrence rate is a major problem. A possible cause of non-healing is local infection of the flap. The aim of this study was to evaluate whether local antibiotic treatment with gentamicin-collagen improves healing after endoanal advancement flap repair for anal fistula. Methods: Eighty-three patients (52 men and 31 women; mean age 47 (range 17-71) years) who had endoanal advancement flap repair for anal fistula between September 1998 and January 2004 were randomized to surgery with (42 patients) or without (41 patients) application of gentamicin-collagen beneath the flap. Patients were evaluated at 1-3 and 12 months after surgery for healing and/or recurrence. Results: The overall healing rate with no recurrence at 1 year after surgery was 57 per cent (47 of 83). Twenty-six of 42 patients randomized to gentamicin-collagen healed primarily compared with 21 of 41 patients randomized to surgery only. There were no overall differences in healing rate according to sex, previous fistula surgery, complexity of fistula, smoking habit or body mass index. Conclusion: Endoanal advancement flap repair for anal fistula has a fairly high primary recurrence rate. Healing was not significantly improved by local application of gentamicin-collagen.