Dr.Aster : Welcome to my show. Topic of the day is Anal fistula. An anal fistula is a small tunnel that develops between the end of the bowel and the skin near the end of the digestive tract. They're usually the result of an infection near the anus causing a collection of abscess in the nearby tissue. When the pus drains away, it can leave a small channel behind. Anal fistulas can cause unpleasant symptoms, such as discomfort and skin irritation, and won't usually get better on their own. Surgery is recommended in most cases. The aim of surgery is to heal the fistula while avoiding damage to the sphincter muscles, the ring of muscles that open and close the anus. Thank you.