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.

This study is a prospective, randomized, controlled, parallel-group surgical trial designed to evaluate and compare the efficacy and functional outcomes of two sphincter-preserving techniques for the management of high perianal fistula: the staged Fistula Rerouting Technique (FRT) and the Ligation of Intersphincteric Fistula Tract (LIFT) procedure.

Background and Rationale:

High perianal fistulas, particularly trans-sphincteric and extrasphincteric types, pose a significant surgical challenge. Traditional fistulotomy carries a high risk of postoperative fecal incontinence due to the division of a substantial portion of the anal sphincter complex. Consequently, sphincter-preserving techniques have been developed. The LIFT procedure, introduced in 2007, achieves closure of the fistula tract via an intersphincteric approach. The FRT, described earlier, employs a staged strategy to physically transpose the fistula tract to a safer intersphincteric plane before its division. While both techniques aim to eradicate the fistula while minimizing injury to the continence mechanism, direct comparative evidence regarding their relative effectiveness, recurrence rates, and impact on postoperative continence is lacking in the literature. This trial aims to fill this evidence gap.

Objectives:

The primary objective is to compare the postoperative recurrence rate of high perianal fistula between the FRT and LIFT groups. The secondary objective is to compare the rate of postoperative fecal incontinence between the two techniques. Additional outcomes include time to wound healing, incidence of surgical site infection, postoperative pain scores, patient-reported quality of life related to incontinence, and time to return to normal activities.

Methodology Overview:

Eligible adult patients (aged 20-65 years) diagnosed with a high perianal fistula at Kasr-Alainy Teaching Hospital will be enrolled. Key exclusion criteria include preoperative incontinence, inflammatory bowel disease, and complex branching fistulas. After providing informed consent, participants will undergo preoperative assessment including clinical examination, MRI fistulogram for tract mapping, and baseline continence scoring using the Cleveland Clinic Fecal Incontinence Score (CCFIS).

Participants will be randomly allocated in a 1:1 ratio to either the FRT group or the LIFT group using a computer-generated randomization sequence with allocation concealment.

FRT Group: Participants will undergo the two-stage procedure as described. The second-stage fistulotomy will be performed only after complete healing of the first-stage wound.

LIFT Group: Participants will undergo the single-stage LIFT procedure.

All surgeries will be performed by experienced colorectal surgeons. A standardized postoperative care and follow-up regimen will be applied to all participants, with scheduled assessments at 1 week, 2 weeks, 1 month, 3 months postoperatively. These assessments will include clinical evaluation for recurrence, wound inspection, CCFIS scoring, patient-reported outcome measures, and documentation of any complications or re-interventions. A follow-up MRI will be performed if clinical recurrence is suspected.

Statistical Considerations:

A sample size of 20 patients per group (40 total) has been calculated based on estimates of recurrence rates for high fistulas. Data will be analyzed on an intention-to-treat basis. The findings of this study are expected to provide Level I evidence to help guide surgical decision-making for this complex condition, balancing the goals of fistula eradication and functional preservation.

Inclusion Criteria:

• Adult patients (age 20-65 years) presenting with a high perianal fistula, defined as:Trans-sphincteric fistula tract traversing the upper two-thirds of the external anal sphincter, Or Extrasphincteric fistula.
• Patients with recurrent perianal fistula.
• Ability to provide informed consent.

Exclusion Criteria:

• Patients with preoperative fecal incontinence (as assessed by the Cleveland Clinic Fecal Incontinence Score).
• Diagnosis of inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
• Pregnant women.
• Pediatric patients (age < 20 years).
• Patients with complex, branching fistula tracts.
• Any contraindication to spinal/general anesthesia or surgery.