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* = Presenting author

P551 Smooth Seton® for perianal fistulas: a knot-less solution

Stellingwerf M.*1, de Groof J.1, Buskens C.1, Nerkens W.2, Horeman T.2, Bemelman W.1

1AMC, Surgery, Amsterdam, Netherlands 2MediShield B.V., Delft, Netherlands


Perianal fistulas are a common incapacitating problem. Many patients are treated by seton drainage to prevent recurrent abscess formation. For centuries, a vessel loop or suture has been used for seton drainage. The knot (or suture) that is necessary to tie both ends together, is well known for causing complaints interfering with daily quality of life. To inventory complaints associated with knotted setons, a web-based questionnaire was performed by the Dutch Crohn and Ulcerative Colitis Association (CCUVN). Twenty-four out of 46 patients (52%) reported to have daily complaints of pain, irritation, itchiness or discharge caused by the knot. Medishield B.V. designed a knotless seton, the Smooth Seton, in order to decrease these complaints. With this study we aim to determine the advantages of a Smooth Seton for patients with perianal fistulas.


A prospective cohort study was performed in a consecutive series of fistula patients. All patients ≥18 years, with perianal fistulas and a seton in situ, or patients presenting with a new perianal fistula, and no defunctioning stoma, were eligible. Existing setons were replaced at the outpatient clinic whereas new setons were placed at the operating theatre in day care setting. The primary outcome was seton failure (loosening of the connection). Secondary outcomes were complications, and quality of life measured by the PDAI (“Perianal Disease Activity Index”). For the patient group with seton replacement, preoperative PDAI was compared to postoperative PDAI. Results were analysed using the paired t-test.


Twenty patients (40% male, mean age 42 (SD 12.81)), were included between August and November 2016. Seventeen patients had perianal fistulas due to Crohn's disease and 3 had fistulas of cryptoglandular origin. In one patient, the outpatient replacement failed, and the Smooth Seton was placed subsequently in theatre. The median number of Smooth Setons placed per patient was 2 (range 1–3). Follow-up was performed in 17 patients with a median of 23 days (range 11–71). Loosing of the connection occurred in one of the patients. Mean PDAI in patients with a knotted seton was 11.36 versus 8.69 after Smooth Seton placement (p=0.006). Looking at each of the 5 subscales of the PDAI, only pain significantly decreased (p=0.003). Ten out of 16 patients (63%) reported less cleaning problems with the Smooth Seton when compared to the regular knotted seton. No postoperative complications occurred during the study period.


The Smooth Seton is a feasible novel technique for patients with new and recurrent perianal fistulas with promising short term results. Replacement of the conventional knotted seton by the Smooth seton significantly decreases complaints measured by the PDAI.