A Prospective, Single-Arm Study to Evaluate the Safety and Efficacy of an Autologous Blood Clot Product in the Treatment of Anal Fistula

BACKGROUND: Surgical treatment of complex perianal fistula is technically challenging, associated with risk of failure, and may require multiple procedures. In recent years, several biologic agents have been developed for permanently eradicating anal fistulous disease with variable success. In this study, the treatment is an autologous whole-blood product created from the patients' blood. It forms a provisional matrix that was found to be safe and effective in healing acute and chronic cutaneous wounds. OBJECTIVE: The study aimed to assess the efficacy and safety of an autologous blood clot product as a treatment for transsphincteric perianal fistulas. DESIGN: A prospective single-arm study. SETTINGS: A single tertiary medical center. PATIENTS: Patients with simple or complex transsphincteric fistulas confirmed by MRI were included in the study. Cause was either cryptoglandular or Crohn's disease related (in the absence of active luminal bowel disease). INTERVENTION: The outpatient procedure was performed under general anesthesia and consisted of: 1) physical debridement and cleansing of the fistula tract; 2) suture closure of the internal opening; and 3) instillation of the autologous blood clot product into the entire tract. MAIN OUTCOME MEASURES: Safety and efficacy at 6- and 12-months after surgery. RESULTS: Fifty-three patients (77% men) with a median age of 42 (20-72) years were included in the study. Three patients withdrew consent, and 1 patient was lost to follow-up. At the time of this interim analysis, 49 and 33 patients completed the 6- and 12-month follow-up period. Thirty-four of the 49 patients achieved complete healing (69%) at 6 months, but 20 of the 33 patients (60%) achieved healing after 1 year. All patients who achieved healing at 6 months remained healed at the 1-year mark. In a subgroup analysis of patients with Crohn's disease, 7 of 9 patients completed 1-year follow-up, with 5 patients (71%) achieving clinical remission. No major side effects or postoperative complications were noted, but 2 adverse events occurred (admission for pain control and coronavirus 2019 infection). LIMITATIONS: Noncomparative single-arm pilot study. CONCLUSIONS: Treatment with an autologous blood clot product in perianal fistular disease was found to be feasible and safe, with an acceptable healing rate in both cryptoglandular and Crohn's disease fistula-in-ano. Further comparative assessment is required to determine its potential role in the treatment paradigm of fistula-in-ano. See Video Abstract.