The word fistula refers to the relationship between two or more surfaces or holes in the body. Anal or perianal fistula is a connection between the inside of the anus and the skin around the anus. That can be a simple, short-lived relationship, or a deep, complex relationship and a lot of detours. Dr. Hossein Yousef fam has been given a detailed explanation of the cause of perianal or anal fistula and its treatment.