Subcutaneous incision of the fistula tract and internal sphincterotomy (SIFT-IS): a novel surgical procedure for transsphincteric anal fistula.

Aim: The aetiology of anal fistula has not been fully clarified. One of the causes of anal fistulas may be the markedly deep crypts that characterize the primary openings. We developed subcutaneous incision of the fistula tract and internal sphincterotomy (SIFT-IS) to eradicate these deep crypts. The aim of this study was to evaluate outcomes in patients with anal fistula treated with SIFT-IS.

Method: A retrospective study was performed over a 2-year period. Patients with transsphincteric anal fistula who underwent SIFT-IS were enrolled. The primary endpoint was the anal fistula healing rate at 16 weeks postoperatively. The secondary endpoints were healing time, postoperative complications and clinical continence status.

Results: One hundred and fifty one patients were enrolled. Primary healing was accomplished in 129 patients (85%). There were 17 patients (11%) with a remnant fistula and five (3%) with a recurrence. The remnant fistulas healed spontaneously at more than 16 weeks postoperatively in seven patients. The median healing time was 6 (3-96) weeks. Surgical intervention was required in seven patients with a remnant fistula and four with recurrence. At the final follow-up, the wounds had healed in 148 patients (98%). No significant postoperative complications or incontinence were observed.

Conclusion: Subcutaneous incision of the fistula tract and internal sphincterotomy is a promising surgical option for transsphincteric anal fistulas, with a satisfactory healing rate.