A series of seton techniques involving "top-down therapy" for patients with Crohn's disease who initially presented with perianal fistulas

Abstract

Objectives: We determined the outcomes of seton treatment through a series of techniques using biological agents (BIOs) in 18 patients with Crohn's disease (CD) who initially presented with perianal fistulas.

Methods: The patients underwent seton drainage using three seton types: a Penrose tube for fistulas with massive purulent discharge, a vessel loop for a small amount of discharge, and a rubber band for unproductive fistulas. If the distal end of the fistula extended more than 4 cm from the anal orifice, the skin and subcutaneous tissue were dissected along the outer edge of the anal sphincter to divide the fistulous tract into two portions. One seton encircled the sphincter from the primary opening throughout the anal canal (medial seton), and the other was inserted through the distal tract outside the sphincter (lateral seton). A BIO was then introduced immediately. When discharge ceased, the Penrose tube or vessel loop was replaced sequentially with a rubber band, which was tied fittingly and subsequently removed in medial to lateral order.

Results: The mean interval between fistula onset and CD diagnosis was 2.1 years, and that between CD diagnosis and introduction of BIOs was 0.5 years. The mean follow-up duration was 4 years. The BIOs currently used were infliximab in 10 patients, adalimumab in 7, and ustekinumab in 1. The overall success rate was 94.4%, including unproductive fistulas in 10 (55.6%) patients and fistula disappearance in 7 (38.9%).

Conclusions: Our seton drainage techniques via the "top-down" approach represent a promising avenue for treating perianal fistulas in patients with CD.

Keywords: Crohn's disease; biological agents; perianal fistula; seton.

Figure 1.

Fistula-dividing technique. (a) When the distal end of a fistula extended more than approximately 4 cm from the anal orifice, the skin was incised at the outer edge of the external sphincter muscle. (b) Subsequently, subcutaneous tissue was dissected upward along the outer side of the sphincter to divide the fistulous tract into two portions for seton insertion; a black arrow shows the Penrose medial seton encircling the sphincter muscles from the primary opening throughout the anal canal, and a white arrow shows the lateral seton inserted through the distal fistulous tract outside the sphincter. However, insertion of the medial seton was avoided as long as the primary lesion was not obviously opened with draining. (c) The seton was subsequently removed in order, from the medial to lateral setons. Using the railroad technique, the Penrose lateral seton was replaced with a rubber band, which was tied repeatedly with moderate tension to keep the rubber band fitted to the skin (“fittingly tied seton technique”). (d) The “lateral seton” was finally removed when its fistulous tract migrated toward the skin, becoming a subcutaneous tunnel (gradual migration technique).

Figure 2.

Railroad technique. (a) A Penrose indwelling lateral seton placed in the right posterior buttocks. The fistula became unproductive after the introduction of UST. (b) A Penrose loop was cut using scissors, and the tip of a rubber band was inserted into the lumen of the Penrose tube. (c) A Penrose seton was replaced with a rubber string without anesthesia (railroad technique). (d) The rubber band was tied with moderate tension to the skin using a 3-0 braided nylon suture (“fittingly tied seton technique”).