Evaluation of the effectiveness of the TROPIS (transanal opening of intersphincteric space) technique in complex anal fistula

Complex anal fistulas represent a challenging disease process, characterized by a sophisticated pathophysiology rooted in the cryptoglandular theory, which has evolved alongside historical advancements in surgical understanding. Effective management requires an integrated approach to classification and treatment, with the dual goals of preventing recurrence and minimizing complications. The TROPIS (Transanal Opening of the Intersphincteric Space) technique, a relatively novel surgical method, aims to eliminate pathogenic agents by transanally opening the intersphincteric space, while preserving sphincter function and reducing the risk of incontinence. In this study, 44 patients meeting the inclusion criteria were treated with the TROPIS technique for complex anal fistula at Pamukkale University between January 2022 and January 2025. Patients were discharged on postoperative day one and monitored monthly for the first three months, followed by biannual follow-ups after complete healing. Outcomes assessed included wound healing, presence of discharge, epithelialization, and complication rates. The cohort comprised 77.3% male and 22.7% female patients, with a mean age of 44.66 ± 11.6 years and a mean BMI of 29.7 ± 4.7. The average healing time was 2.1 months. Fistula types were classified as transsphincteric (72.7%), intersphincteric (22.7%), and extrasphincteric (4.5%). Uneventful healing occurred in 86.4% of patients, while 13.6% experienced delayed healing, with symptoms such as persistent discharge, delayed epithelialization or rectal pain. At six-month follow-up, 70.5% of patients achieved complete healing without recurrence, whereas 29.5% experienced recurrence. One patient reported gas incontinence, resulting in an overall continence preservation rate of 97.7%. Statistical analysis demonstrated a significant association between the number of fistula tracts and prolonged healing time (p = 0.006). In conclusion, the TROPIS technique demonstrates high continence-preserving efficacy and favorable therapeutic outcomes in the treatment of complex anal fistulas. Increased fistula complexity, such as a higher number of tracts or horseshoe configurations, was associated with longer healing times and higher recurrence rates. These findings support the role of TROPIS as an effective sphincter-sparing option in the surgical management of complex anal fistulas. Keyword: complex anal fistula, TROPIS, sphincter-sparing surgery, recurrence, continence.