¹ Division of Colorectal Surgery, Department of Surgery, Faculty of Medicine, Chiang Mai University Hospital, Chiang Mai, Thailand; ² Clinical Surgical Research Center, Department of Surgery, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; ³ Center of Clinical Epidemiology and Clinical Statistic, Faculty of Medicine. Chiang Mai University, Chiang Mai, Thailand; ⁴ Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand

Background: Cryptoglandular infection is one of the main causes of common anorectal infections that presents in conjunction with abscess following anal fistula after drainage.

Objective: To evaluate the rate and predictive factors of fistula formation following anorectal abscess drainage, and the timing of fistula diagnosis.

Materials and Methods: The present study was a retrospective study of 232 patients with cryptoglandular anorectal abscess that underwent drainage in the operating room under anesthesia between 2010 and 2019. The predictive factors of fistula development were analyzed using Cox’s proportional hazard.

Results: Seventy out of 232 patients (30%) developed anorectal fistula after drainage of anorectal abscess. Median follow-up time was 35.5 months, and 25.02% (95% CI 19.89 to 31.19) of patients developed fistula within 12 months after the surgery. Independent factors in developing anal fistula after drainage were female gender (HR 2.17, 95% CI 1.15 to 4.14, p=0.017), alcohol consumption (HR 2.24 95% CI 1.20 to 4.22, p=0.012), and driver (HR 2.80, 95% CI 1.08 to 7.25, p=0.034). The protective factors are gauze packing (HR 0.43, 95% CI 0.23 to 0.82, p=0.009) and identifiable organism from pus culture (HR 0.59, 95% CI 0.36 to 0.99, p=0.046).

Conclusion: After drainage of a cryptoglandular anorectal abscess, there is a need to raise the awareness concerning anorectal fistula in female patient, alcohol drinkers, and those who work as drivers. Bacterial cultures should be taken, and gauze drain should be positioned. The potential fistula formation should be monitored in the first year after the operation with an option of extending to a second year.

Received 11 January 2024 | Revised 20 March 2024 | Accepted 29 March 2024

DOI:10.35755/jmedassocthai.2024.5.13979