Perianal fistulas are a chronic anorectal condition associated with significant morbidity, including pain, persistent discharge, infection, and impaired continence, all of which can substantially affect patients' quality of life. Surgical management aims to eradicate the fistulous tract while preserving anal sphincter function and continence.

Despite numerous available surgical techniques, high-quality comparative evidence regarding optimal management remains limited. This prospective observational study aims to evaluate clinical outcomes, functional outcomes, and patient-reported quality of life following surgical treatment of perianal fistulas.

The study will collect both clinician-reported and patient-reported outcomes over a 12-month follow-up period. Outcomes of interest include fistula healing, recurrence, postoperative complications, continence status, symptom burden, and health-related quality of life. The findings are expected to provide real-world data that may inform clinical decision-making and contribute to improved patient-centered care.

Background

Perianal fistulas are abnormal tracts that connect the anal canal or rectum to the perianal skin, most often developing after a perianal abscess that originates near the anal glands at the dentate line. The majority of fistulas arise secondary to an abscess. Treatment aims to eradicate the tract, prevent recurrence, and preserve continence by protecting the sphincter mechanism. Fistulas are classified anatomically (Parks) and, more clinically, as simple (low) or complex. Simple fistulas involve only the distal third of the external sphincter and are usually cured with sphincter-dividing procedures such as fistulotomy or fistulectomy, which have high healing rates and low continence risk. Complex fistulas-those that affect a larger portion of the sphincter, have multiple tracts, or are recurrent-require sphincter-preserving techniques (e.g., mucosal advancement flap, LIFT, laser treatment, plugs, or setons), although these approaches often carry higher recurrence rates. Current guidelines are hampered by limited high-quality evidence and marked heterogeneity in outcome definitions, measurement tools, and reporting practices, highlighting the need for standardized prospective data.

Study Objective and Design

The primary aim is to generate high-quality, real-world observational data on surgical management of perianal fistulas. The study will conduct a prospective cohort enrolling adult participants at the time of definitive fistula surgery and will follow them for 12 months. The cohort will be stratified by fistula complexity (simple vs. complex) and by surgical strategy (partially sphincter-dividing versus sphincter-preserving). The study will capture demographic, clinical, imaging, and operative information to explore how these variables relate to healing, recurrence, continence preservation, and patient-reported quality of life.

Data Collection and Analysis

Baseline data will include age, sex, comorbidities, pre-operative imaging, and any preceding seton placement or previous surgery. Operative details-type of technique, extent of sphincter involvement, intra-operative findings-will be recorded in a standardized case-report form. Follow-up assessments will occur at 1, 3, 6, and 12 months post-operatively and will collect clinician-reported endpoints (clinical and radiological healing, recurrence, complications graded by Clavien-Dindo) and patient-reported outcomes (continence status, symptom burden, health-related quality of life, psychological impact, and satisfaction) using validated instruments. Descriptive statistics will summarize patient and treatment characteristics; multivariable logistic and Cox regression models will evaluate associations between surgical approach, imaging findings, and outcomes, adjusting for confounders such as age, comorbidity, and fistula complexity. Subgroup analyses will compare outcomes across the two surgical strategy groups.

Anticipated Impact

By employing uniform outcome definitions and integrating both clinician- and patient-centered metrics, the study will fill a critical evidence gap regarding the comparative effectiveness of current fistula surgeries. The findings are expected to clarify which techniques achieve optimal healing while minimizing continence loss and to provide robust data that can refine clinical guidelines, inform shared-decision making, and ultimately improve functional and quality-of-life outcomes for patients with perianal fistulas.

Inclusion Criteria:

• Age ≥ 18 years.
• Clinically and/or radiologically confirmed perianal fistula (primary or recurrent).
• Planned definitive surgical treatment (any sphincter-dividing or sphincter-preserving technique).
• Ability to understand and complete study questionnaires.
• Commitment to attend follow-up visits at 1, 3, 6, and 12 months (or to complete remote assessments).
• Signed written informed consent.

Exclusion Criteria:

• Diagnosed inflammatory bowel disease (Crohn's disease or ulcerative colitis).
• Active perianal sepsis requiring emergency drainage after enrolment and before definitive surgery.
• Prior abdominoperineal resection or permanent colostomy.
• Pregnancy or planned pregnancy during the 12-month follow-up.
• Severe uncontrolled systemic disease (e.g., decompensated heart failure, end-stage renal disease, uncontrolled diabetes).
• Cognitive impairment or psychiatric disorder precluding reliable consent or questionnaire completion.
• Lack of reliable contact information or inability to attend at least one scheduled follow-up visit.

The study will enroll adult patients with cryptoglandular perianal fistulas who are scheduled for elective surgical repair. Participants will be free of inflammatory bowel disease and major anorectal resections, and they will be able to provide informed consent, complete validated patient-reported outcome measures, and comply with the scheduled 12-month follow-up protocol.