This clinical trial is focused on studying the effectiveness of a treatment involving amoxicillin/clavulanic acid for patients who have undergone surgery for their first episode of a perianal abscess. A perianal abscess is a painful condition where a collection of pus forms near the anus. The treatment aims to prevent the development of an anal fistula, which is an abnormal connection that can form between the end of the bowel and the skin near the anus after an abscess.

The purpose of the study is to determine if taking the antibiotic combination of amoxicillin trihydrate and potassium clavulanate after surgical drainage of the abscess can effectively prevent the formation of an anal fistula. Participants in the study will be randomly assigned to receive either the medication or a placebo. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual medication or the placebo, ensuring unbiased results.

Throughout the study, participants will be monitored for the development of an anal fistula and other related outcomes, such as the time it takes for a fistula to appear, the complexity of any fistula that does develop, and the need for further surgery. The study will also assess the quality of life of participants using a specific questionnaire. The trial is expected to continue until the end of 2027, with the goal of providing valuable insights into the prevention of anal fistulas following a perianal abscess.