Loss of seton in patients with complex anal fistula: a retrospective comparison of conventional knotted loose seton and knot-free seton.

Abstract

Loose setons are often utilized. Replacements after seton loss are frequent, but the exact incidence of this loss of seton (LOS) in patients is unknown. The aim of the present study was to assess the incidence of LOS in a population with complex anal fistula, comparing the knot-free loose seton with the conventional knotted loose seton. All consecutive patients treated with a loose seton for complex anal fistula in two large teaching hospitals in the Netherlands between January 2017 and December 2019 were included in the present study. The incidence of loss of a conventional knotted loose seton was compared with the loss of commercially available knot-free setons. There were 212 patients. Fifty-two patients were included in the knotted loose group and 160 patients were included in the knot-free seton group. Sixteen patients who were treated with both a knotted and a knot-free loose seton were included in both groups. The incidence of LOS was 12% in the knotted seton group and 28% in the knot-free loose seton group (p = 0.02). Median time to LOS was 36days for the knotted loose seton and 89days for the knot-free loose seton (p = 0.36). Sex (p = 0.61), age at the time of seton placement (p = 0.60), and presence of inflammatory bowel disease (p = 0.28) were not significantly associated with LOS. LOS occurs frequently in patients treated for complex anal fistulas. The incidence of LOS is significantly higher in patients treated with a knot-free loose seton. Further developments in seton manufacturing should be focussed on optimisation of the closure mechanism.