QS115 - A Retrospective study on LIFT versus Fistula Occlusion with the Internal Sphincter Flap (FOISF) in treatment of complex anal fistula

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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-fistula occlusion with the internal sphincter flap (FOISF)-developed by our expert team.

Methods/Interventions: This retrospective comparative analysis aimed to compare fistula occlusion with the internal sphincter flap (FOISF) and ligation of the intersphincteric fistula tract (LIFT), in the treatment of high complex anal fistula in terms of the success of treatment and safety. From November 2020 to March 2023, a total of 80 patients underwent FOSIF(n=32) and LIFT(n=48) procedures. The main outcome measures were healing rate, time to healing, recurrence time, operation time, and quality of life.The surgical procedures are described as below:
FOISF:
①Identifying the internal opening (IO): the IO was located by administering a low dose of methylene blue with hydrogen peroxide through injection via a superficial vein catheter from the external opening (EO)；
②Excision of the fistula from EO to EAS: A tunnel-like core fistulectomy was performed from the superficial of the EO into the ischiorectal fossa, ending at the entrance infixed into the EAS or puborectal muscle；
③Dissection of the intersphincteric plane: A reversed T-shape incision was made at the intersphincteric plane and resection of IO and closure of the transphincteric tract by 2-0 absorbable sutures with eight stitches was accomplished, followed by occlusion with the internal sphincter flap with absorbable continuous barbed sutures.
LIFT:
①An incision was made at the intersphincteric groove and blunt dissection was undertaken in the intersphincteric plane to identify the intersphincteric fstula tract;
②The fistula tract was ligated twice with polyglactin 2/0 sutures and the part of the tract between the two ligatures was excised using scissors.
③Curettage of the granulation tissue in the intersphincteric space and the external fistula opening was conducted and the intersphincteric incision was finally closed with polyglactin 2/0 sutures.

Results/Outcomes: Over a follow-up of 18 months, there were no fecal incontinence with this case reporting. A cohort of eighty patients（83.7%males）of mean age of 37.03 years were included in this study. FOISF had a significantly higher primary healing rate than LIFT (78.1%vs39.6%, p=0.01). Mean operation time of FOISF and LIFT were essentially equivalent. (53.6± 3.9vs51.8±2.6p＞0.05).We performed reoperations on patients who had failed treatments. The overall heating rates for the two surgical methods are comparable（87.1%vs79.2%, p＞0.05）.The average time to healing after FOISF was shorter than the LIFT (106.5±27.5vs112±35.7 p=0.358). But the LIFT procedure is more prone to recurrence（344±127.1 vs 406.5±48.5，p=0.165）. The two procedures achieved similar quality of life.

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.