High Perianal Fistula

High perianal fistulae involve a significant portion of the external anal sphincter muscle, making standard surgical fistulotomy risky due to the potential for postoperative fecal incontinence. Sphincter-preserving techniques aim to eradicate the fistula tract and promote healing while safeguarding anal continence. The purpose of this prospective, single-arm clinical study is to evaluate the efficacy and safety of the two-stage seton re-routing technique in adult patients diagnosed with high perianal fistula at Assiut University Hospital. The procedure is conducted in two stages: * First Stage: Identification and curettage of the fistula tract followed by placement of a loose draining seton to clear local sepsis and allow fibrous maturation over an interval of 6 to 12 weeks. * Second Stage: Creation of a low submucosal or intersphincteric tunnel beneath the main external anal sphincter complex. The seton is unthreaded and re-routed through this lower pathway, isolating the upper transsphincteric tract so it can heal spontaneously by secondary fibrosis. The resulting downstaged superficial tract is then laid open (low fistulotomy) or managed with staged seton tightening. Participants will be monitored weekly during the first month, followed by regular monthly follow-up visits for a minimum of 6 to 9 months postoperatively. The study assesses complete fistula healing, recurrence rates, healing time, operative duration, postoperative complications, and anal continence status evaluated using the Cleveland Clinic (Wexner) Incontinence Score preoperatively and at 3, 6, and 9 months after surgery.

The goal of this clinical trial is to compare two different surgery methods for treating a complex type of anal fistula. This condition is an abnormal tunnel connecting the inside of the anus to the skin nearby. The main questions the study aims to answer are: Which surgery has a lower chance of the fistula coming back (recurrence)? Which surgery has a lower chance of causing problems with bowel control (incontinence) after healing? Researchers will compare two surgery groups: Group 1: Fistula Rerouting Technique - a two-step surgery that moves the fistula tract to a safer area before opening it. Group 2: LIFT Technique - a surgery that ties off and closes the fistula tract from between the anal muscles. Participants will be randomly assigned by a computer to one of these two surgery groups. This helps ensure the comparison between the two surgeries is fair. Participants in this study will: * Have tests before surgery, including an MRI scan, to confirm they have the specific type of fistula being studied. * Undergo one of the two planned surgical procedures. * Attend follow-up visits after surgery at 1 week, 2 weeks, 1 month, and 3 months. * Be checked during these visits for wound healing, pain, infection, and bowel control. * Have another MRI scan if the fistula is suspected to have come back.