Loose Seton Prior to Surgery for Single-tract Cryptoglandular Fistula vs no Seton

Cryptoglandular anal fistulas can cause pain, discharge, recurrent infection, and a prolonged treatment course. In current practice, patients with a single-tract mid-high or high cryptoglandular anal fistula often first undergo placement of a loose seton before definitive sphincter-preserving surgery. Although this staged approach is widely used, high-quality evidence showing that preoperative seton placement improves healing or other patient outcomes is limited. The SETON trial is a multicenter, randomized, controlled non-inferiority trial that compares two accepted treatment strategies: loose seton placement for approximately 8 weeks followed by definitive sphincter-preserving surgery versus direct sphincter-preserving surgery without prior seton placement. The study aims to determine whether omitting routine seton placement is not inferior in terms of fistula closure 26 weeks after the final surgical intervention. Secondary outcomes include recurrence, postoperative complications, re-interventions, pain, continence, fistula-related quality of life, generic quality of life, return to work, and healthcare and societal costs. The results of this trial may help determine whether a routinely used treatment step can be safely omitted, potentially reducing treatment burden, shortening the treatment pathway, and lowering costs.

Inclusion Criteria: * Age 18 years or older * Single-tract non-purulent mid-high or high cryptoglandular anal fistula * Eligible for sphincter-preserving surgical treatment * Able to complete Dutch-language questionnaires sent by email * Written informed consent provided Exclusion Criteria: * Anorectal abscess * Multiple or complex anorectal fistulas * Inflammatory bowel disease or clinical suspicion requiring further investigation * History of anorectal malignancy * Use of immunosuppressive medication at the time of surgery * History of pelvic radiation * Pregnancy or lactation