A fistula is an abnormal tunnel or connection between two body parts that shouldn't be connected, like an organ and the skin or two organs, often forming after infection or inflammation ( Black Friday Bundle Shooter Lube Avens Publishing Group Anal Fistula Repair with Acellular Dermal Matrix Plug: Description of a Novel Technique and Early Results View of Recent developments in the surgical management of perianal fistula for Crohn's disease Annals of Gastroenterology