FISTULA-RFA Trial: Radiofrequency Ablation for Perianal Fistula

The goal of this pilot clinical study is to learn whether radiofrequency ablation (RFA) can safely and effectively treat perianal fistulas in adults. It will also evaluate procedure-related safety and changes in symptoms over time. The main questions it aims to answer are: * How many participants achieve fistula closure by 6 months after RFA treatment? * How often do fistulas recur during follow-up? * What medical problems or adverse events occur after the RFA procedure (for example, pain, bleeding, infection, urinary retention, or changes in continence)? * How do patient-reported outcomes (such as pain and quality of life) change after treatment? This is a prospective, multicenter, single-arm pilot study. All participants will receive RFA treatment; there is no comparison (control) group. Participants will: * Be screened and enrolled at one of the participating hospitals * Undergo a standardized RFA procedure for the perianal fistula * Attend follow-up visits with clinical assessments at regular time points up to 6 months (including key assessments around 3 and 6 months) * Report symptoms and any adverse events during the follow-up period