PURPOSE: The role of antibiotics in preventing fistula formation following an initial abscess remains a subject of debate. This study compared the incidence of fistula in ano in patients experiencing their first episode of acute perianal sepsis, with and without antibiotic therapy, and evaluated the prevalence of fistula in ano necessitating surgical intervention at 1 year. METHODS: This retrospective cohort study was conducted at a tertiary care hospital with a dedicated proctology department. All patients who presented to the emergency proctology unit with a first episode of acute perianal sepsis were eligible for inclusion. RESULTS: This study included 276 patients. At 1 year, fistula formation was identified in 65.6% of all patients, 54.0% of those who had received antibiotics, and 75.0% of those who had not (P<
0.001). This finding remained significant after weighted propensity analysis (odds ratio, 0.53
95% confidence interval, 0.31-0.92
P=0.025). CONCLUSIONS: The rate of fistula formation was relatively high in this study. However, it was lower among patients with perianal sepsis who were treated with antibiotics, although a causal relationship could not be established. Prolonged follow-up is needed to clarify the role of antibiotic therapy in preventing or delaying fistula development in patients with acute perianal sepsis.