eP414 - Extracellular Matrix for the Treatment of Anal Fistula: A Single Center Retrospective Review

Purpose/Background: Anal fistula is an inflammatory tract connecting the anal canal to the perianal skin. Fistulas typically arise from prior cryptoglandular infection, but are also present in inflammatory bowel disease, obstetric injury and radiation proctitis. Surgery is the standard approach with the goal of clearing infection and allowing for the tract to heal without compromising anal sphincter function. There is a wide variety of techniques available, and each is chosen based on the fistula anatomy. The use of extracellular matrix (ECM) technologies for tissue regeneration has been widely reported in the surgical literature. Ovine forestomach matrix (OFM) is an ECM technology developed for complex plastic and reconstructive procedures which has previously been evaluated for the treatment of anal fistula with promising results. Having recently adopted the use of OFM graft for the treatment of fistula, we undertook a retrospective chart review to assess healing rates and recurrence using this approach.Methods/Interventions: We conducted a retrospective review of patients in our institution who underwent repair of anal fistula with an OFM graft. Patients were identified in the electronic medical record and risk factors, previous interventions, and healing time were identified.Surgical technique was standardized between the surgeons at our institution, all patients first had the defect size measured intraoperatively. The tract was then curetted with gauze. Following this, the OFM graft was placed into the defect, and sutured to the internal opening with 3-0 polydioxanone suture (PDS). The wound was then dressed with Xeroform® and gauze. Patients followed up at 1 week, 1 month, 3 months, and 6 months. We assessed time to healing, recurrence, complications (infection, bleeding). Descriptive statistics (e.g. mean, median, standard deviation (SD) were computed with GraphPad Prism (v10.0.3).Results/Outcomes: We identified 25 patients who underwent the procedure in our institution. The mean age of patients was 48.3 years old (SD=14.9). The mean depth of the fistula tract was 3.34 cm (SD=1.58). Thirteen patients had a seton used preoperatively with a mean time of 20.6 weeks in use (SD=30.5). The mean time to heal was 4.68 weeks (SD=1.13). No patients were lost to follow up. 88% (n=22/25) of the patients were healed within the study period (47 weeks). 12% (n=3/25) did not heal. 4% (n=1/25) patients had a recurrence. There were no adverse effects reported.Conclusion/

Discussion: In this study, we describe our institution’s experience using an OFM graft to treat anal fistula. A prior retrospective study has previously been reported using this approach and demonstrated that the technique was efficacious. Notably, in comparison to the prior research, our study had a larger sample size (n=25 vs n=14), with lower recurrence rates. One major difference that may have contributed to the lower recurrence rate was the usage of PDS instead of Vicryl®. Regardless, this study adds to the body of evidence to support the use of an OFM graft for the treatment of anal fistula.Figure 1.Figure 1. (A) OFM graft sewn in place with interrupted PDS. (B) Xeroform® dressing over surgical site.