Anal fistula, or fistula-in-ano, is a chronic abnormal communication between the epithelialised surface of the anal canal and the perianal skin. An anal fistula can be described as a narrow tunnel with its internal opening in the anal canal and its external opening in the skin near the anus. Anal fistulae commonly occur in people with a history of anal abscesses. They can form when anal abscesses do not heal properly. Anal fistulae originate from the anal glands, which are located between the in