Transanal Opening of the Intersphincteric Space to Treat Anal Fistula: A Systematic Review and Meta-Analysis

Transanal opening of the intersphincteric space (TROPIS) is a minimally invasive surgical treatment for anal fistula that not only eliminates the source of infection but also protects anal function to the greatest extent. This systematic review and meta-analysis aims to evaluate the efficacy of TROPIS in the treatment of anal fistula.

We searched PubMed, EMBASE, Web of Science, and the Cochrane Library for information on TROPIS surgery for anal fistulas performed between the inception of each database and 1 November 2024. We used the single-arm studies for analysis, with a total of 918 subjects and a follow-up period ranging from 3 months to 36 months. The analysis focused on the cure rate of different types of anal fistula, postoperative bleeding, infection, and adverse reactions.

This systematic review included six single-arm studies involving a total of 918 patients with anal fistula who underwent TROPIS surgery, with follow-up durations ranging from 3 to 36 months. Among the included studies, all were classified as high quality (score ≥7). This study demonstrated an 80% success rate for the initial operation (95% confidence interval (CI): 0.77-0.83), as well as an 80% success rate specifically for high fistulas (95% CI: 0.77-0.83). The success rate for second operations was 73% (95% CI: 0.47-0.99). For patients with high fistulas who underwent a second procedure, the success rate was 78% (95% CI: 0.40-1.00). The cure rate for anal fistulas accompanied by abscesses was 88%, while the cure rate for anal fistulas without abscesses is the same. For horseshoe fistulas, the cure rate was 87%, whereas it was 88% for non-horseshoe fistulas. The overall cure rate in this study was 88% (95% CI: 0.86-0.90). The rate of intraoperative bleeding was 3%, the postoperative infection rate was 5%, and the overall incidence of adverse reactions was 3%.

This study demonstrates that TROPIS holds significant potential in the treatment of anal fistulas, particularly for high fistulas, fistulas with associated abscesses, and horseshoe-shaped fistulas, whilst exhibiting a relatively low incidence of incontinence.