Loose seton in the treatment of transsphincteric anal fistulas complicated by additional fistula tracks (randomized trial)

AIM: to evaluate caudal migration of free seton in patients with anal fistulas complicated by additional fistula tracks.PATIENTS AND METHODS: the prospective randomized single-center study included 115 patients with transshincteric fistulas, who had one of 2 types of seton installed. The decision to choose a seton was made by randomization in 2 groups: 63 patients with a polyester braided ribbon with a fluoropolymer coating 3 mm wide (Polyester-F Braid 3 mm, “Balumed” LLC, Russian Federation) seton “T”, and the 2nd group included 52 patients with a seton polyester braided ribbon with a fluoropolymer coating with a diameter of 0.5 mm of USP conditional number 2 with a diameter of 0.5 mm was installed (Polyester-F Thread USP 2 with a diameter of 0.5 mm, “Balumed” LLC, Russian Federation) — seton “N”.RESULTS: after 12 weeks the largest number of complete caudal migration occurred in 30/63 (47.6%; 95% CI: 34.9–60.6) patients with seton “T”, whereas in patients with seton “N” it occurred significantly less often in 7/52 (13.5%; 95% CI: 5.6–25.8) patients (p = 0.0002). Caudal seton migration with sphincter involvement of more than 1/2 was noted only in 1 patient with seton “T”, and was completely absent in patients with seton “N”.CONCLUSION: in patients with a fistulas involving less than 1/2 of the external sphincter, it is reasonable to use a 3 mm wide fluoropolymer-coated polyester braided band as a seton, expecting caudal migration in almost half of the cases. Whereas the installation of a 0.5-mm diameter fluoropolymer-coated polyester braided thread, when more than 1/2 of the external sphincter is involved, does not lead to caudal migration.