Long-term outcome of loose seton for complex anal fistula: a two-centre study of patients with and without Crohn's disease

Objective Complex anal fistulas traverse a significant portion of the external sphincter muscle, making their treatment a surgical challenge. Several surgical options are used with conflicting results. The aim of this study was to analyse the results of permanent loose seton in the management of high anal fistulas in Crohn's disease (CD) patients and two-stage seton fistulotomy in patients without CD. Method We retrospectively reviewed the clinical records of 77 patients with complex anal fistula treated by loose seton over a 4-year period, in two medical centres. Recorded parameters included demographics, medical history, type of fistula, disease duration, previous surgery, morbidity, recurrence and mortality. Results Sixty patients without CD underwent 107 fistula-related surgical procedures, and 17 CD patients underwent 29 procedures. Early postoperative complications were recorded in eight (10%) patients. Perioperative complications, mainly local sepsis or bleeding, were recorded in eight (10%) patients. Long-term complications were observed in nine non-CD and four CD patients. During a median follow-up period of 24 months, the recurrence rate was 40% in CD patients and 47% in patients without CD. Five patients (four non-CD patients and one CD patient) developed some degree of faecal incontinence. Conclusion The fistula recurrence rate following two-stage seton fistulotomy in non-CD patients was high. In CD patients the use of permanent loose seton is effective in controlling local sepsis in about half of patients and has low rates of subsequent incontinence.