LB103 - Fistula Occlusion with the Intimal Sphincter Flap (FOISF) in the Treatment of High Complex Anal Fistulas: A Phase III Trial

Presenting Author(s)

• 

  Yiping Li

  Resident physician
  The Sixth Affiliated Hospital of Sun Yat-sen University
  Guangzhou, Guangdong, China (People's Republic)

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose

Author(s)

• KL

  Kun Lu, n/a

  Department of Anesthesia
  6th Affliated Hospital of Sun Yat-sen University
  guangzhou, Guangdong, China (People's Republic)

  Disclosure information not submitted.
• YL

  Yanzhu Li, n/a

  Attending physician
  The people’Hospital of Zhongshan, Zhongshan, China
  zhongshan, Guangdong, China (People's Republic)

  Disclosure information not submitted.
• XL

  Xinrui Lu, n/a

  Department of General Surgery （Coloproctology）
  People's Hospital of HEBI
  Hebi, Henan, China (People's Republic)

  Disclosure information not submitted.
• DH

  Dandan Huang, n/a

  Attending Physician
  The Sixth Affiliated Hospital of Sun Yat-sen University
  guangzhou, Guangdong, China (People's Republic)

  Disclosure information not submitted.
• xw

  xingyang wan, n/a

  Deputy Chief Physician
  The First Affiliated Hospital, Guangzhou University of Traditional Chinese Medicine
  guangzhou, Guangdong, China (People's Republic)

  Disclosure information not submitted.
• 

  donglin Ren, n/a

  professor
  26 Yuancun Erheng Road, Tianhe District, Guangzhou, Guangdong
  Sun-sen University
  guangzhou, Guangdong, China (People's Republic)

  Disclosure information not submitted.
• 

  Hongcheng Lin, PhD

  Chief Physician
  The Sixth Affiliated Hospital of Sun Yat-sen University
  guangzhou, Guangdong, China (People's Republic)

  Disclosure information not submitted.

Senior Author(s)

• 

  Zhimin Liu

  Attending Physician
  The Sixth Affiliated Hospital, Sun Yat-sen University
  Sun Yat-sen University
  guangzhou, Guangdong, China (People's Republic)

  Disclosure information not submitted.

Purpose/Background: Anal fistula is a common anorectal disorder characterized by chronic infection and discharge, which can substantially impair patients' quality of life. Sphincter-sparing techniques represent an ideal surgical strategy for complex anal fistulas, aiming to balance high healing rates with preservation of anal continence. Despite advances, opportunities remain to further optimize treatment efficacy and minimize recurrence. Herein, we introduce a novel enhanced sphincter-preserving procedure-Fistula Occlusion with the Intimal Sphincter Flap (FOISF)-developed by our team specifically for high transsphincteric anal fistulas. The FOISF procedure integrates a fusion-oriented surgical design, with the goal of achieving complete eradication of the intersphincteric pathological focus and maximal excision of the fistulous tract, while prioritizing the maximal preservation of anal sphincter integrity.

Methods/Interventions: This multicenter, prospective, randomized controlled trial (registration number: ChiCTR2300076874) directly compares the efficacy of the novel Fistula Occlusion with the Intimal Sphincter Flap (FOISF) procedure versus the Ligation of the Intersphincteric Fistula Tract (LIFT) for high complex anal fistulas (predominantly transsphincteric or suprasphincteric according to the Parks classification). The study plans to enroll 234 participants in total. For the present interim analysis, 144 patients have been enrolled and randomized to either the FOISF group (n=74) or the LIFT group (n=70).

The primary endpoint was the primary healing rate. Key secondary endpoints included the overall healing rate, time to complete healing (weeks), recurrence rate and time to recurrence, Wexner fecal incontinence score, operative time, and patient-reported quality of life. All procedures were performed by a dedicated team of senior coloproctology surgeons with specialized expertise in fistula surgery. Standardized, structured follow-up protocols were implemented for long-term outcome assessment.

Results/Outcomes: For this interim analysis, all patients had a median follow-up duration exceeding 12 months, with no cases of postoperative anal incontinence observed in either group. A total of 144 patients with high complex anal fistulas were enrolled, of whom 77.8% (112/144) were male, with a mean age of 38 years (see Table). The primary healing rate of FOISF group was markedly superior to that of the LIFT group (78.1% vs. 51.4%, p < 0.05; see Table). Notably, the FOISF group included a significantly higher proportion of more anatomically challenging fistulas, including suprasphincteric fistulas, horseshoe fistulas, and fistulas with multiple internal openings (all p < 0.05), suggesting that the FOISF technique offers a particular advantage in managing the most complex subtypes of high anal fistulas. Following secondary interventions in cases of primary failure, the overall healing rates were comparable between groups (89.2% vs. 85.7%, p > 0.05).

Conclusion/Discussion: The novel FOISF technique is an effective sphincter-preserving approach for complex transsphincteric fistulas. Compared to LIFT, FOISF achieved higher primary healing rates while preserving continence, suggesting a particular advantage for complex subtypes (suprasphincteric, horseshoe, multi-opening). Long-term follow-up is needed to confirm durability and define its role in management.

FOISF and LIFT surgerical procedure
Demographic, clinical, and radiological characteristics of anal fistulas in the study groups