VM77 - Treatment of High Complex Anal Fistulas by Modified External Sphincter-preserving Surgery

Purpose/Background: Anal fistula is a commonly encountered anorectal condition distinguished by chronic infectious symptoms, which can significantly diminish the patients' quality of life. The sphincter-sparing approach appears to be an ideal surgical intervention for the treatment of anal fistulas, as it offers a combination of a high success rate and the preservation of normal anal function. However, it still remains room to improve the treat efficacy. We introduce an enhanced sphincter-saving approach for treating high transphincteric anal fistulas, developed by our expert team.

Methods/Interventions: This study evaluated a cohort of patients with high transphincteric anal fistulas who underwent a novel surgical procedure at a specialized referral institute from October 2021 to December 2022 (n=30).Preparations and Operative Procedure:Clinical examinations, routine laboratory investigations, a digital rectal examination,Colonoscopy(when necessary to assess the condition of the intestine )magnetic resonance imaging (MRI) and anorectal manometry were performed in this patient. Each patient received received an enema the night before surgery.Each patient received intravenous antibiotics before surgery.The patients were experienced with spinal anaesthesia and performed in a prone position. Initially, the internal opening was located by administering a low dose of methylene blue through injection from external opening. An incision was made around the external opening.Fine dissection of fistureciony without huting external sphincter muscle.For fistula tracts that extended beyond and traversed the external sphincter, a tunnel-like core fistulectomy was conducted.Next an inversed “T” shape incision was designed for better exposure of psterior inter-sphincter space.Alice's forceps delicately secured the internal opening, and the intersphincteric tracts, including the suspicious internal opening and the internal sphincter , were precisely resected using electrocautery. Followed by curetting and suturing of the defect that tract crossing the external sphincter.Moreover, a partial rectal wall advancement flap, consisting of mucosa, submucosa, and circular muscle fibbers, was meticulously crafted, extending from the initial internal opening toward cephalad The flap was further advanced to external sphincter (1 cm below the initial tract crossing the external sphincter) and sutured using absorbable sutures (absorbable unidirectional monofilament barbed Statafix). Perfect haemostasis was attained, and a rectal gauze pack was routinely inserted for haemostasis.

Results/Outcomes: Over a follow-up of 6 months , there were no recurrences with this case reporting normal continence.A cohort of thirty patients, was included in this study.All patients underwent modified external sphincter-preserving surgery.Over a follow-up period of at least eleven months (with a median time of 17 months and a range from 11 to 30 months), it was observed that 90% of the patients (n=27) achieved healing. A small subset of patients, accounting for 6.7% (n=2), experienced recurrence at the six-month and two-year post-operation, while a mere 3.3% of patients (n=1) encountered treatment failure.

Conclusion/Discussion: The primary results of the novel technique presents an effective approach to high complex transphincteric anal fistula with high heal rate, minimal pain, and satisfied anal function. We recommend conducting larger prospective studies with longer-term follow-up to further validate these findings.