High complex anal fistula managed by the modified transanal opening of the intersphincteric space via the inter-sphincteric approach: A case report.

Background: High complex anal fistulas are epithelialized tunnels, with the main fistula piercing above the deep external sphincter and the internal opening approaching the dentate line. Conventional surgical procedures for high complex anal fistulas remove most of the external sphincter and damage the anorectal ring. Postoperative loss of anal function can cause physical and mental damage. Transanal opening of the intersphincteric space (TROPIS) is an effective procedure that completely preserves the external anal sphincter. However, its clinical application is limited by challenges in the localization of the internal opening of a fistula and the high risk of complications. On the basis of our clinical experience, we modified the TROPIS procedure for the treatment of treating high complex anal fistulas.

Case summary: A patient with a high complex anal fistula located above the anorectal ring underwent modified TROPIS, which involved sepsis drainage and identification of the internal opening in the intersphincteric space. The patient with the high complex anal fistula recovered well postoperatively, without any postoperative complications or anal dysfunction. Anal function returned to normal after 17 months of follow-up.

Conclusion: The modified TROPIS procedure is the most minimally invasive surgery for anal fistulas that minimally impairs anal function. It allows the complete removal of infected anal glands and reduces the risk of postoperative complications. Modified TROPIS via the intersphincteric approach is an alternative sphincter-preserving treatment for high complex anal fistulas.