An anal fistula is almost always the result of a previous abscess. Just inside the anus are small glands. When these glands get clogged, they may become infected and an abscess can develop. A fistula is a small tunnel that forms under the skin and connects a previously infected anal gland to the skin on the buttocks outside the anus.
After an abscess has been drained, a tunnel may persist connecting the anal gland from which the abscess arose to the skin. If this occurs, persistent drainage from the outside opening may indicate the persistence of this tunnel. If the outside opening of the tunnel heals, recurrent abscess may develop.
Treatment of an anal fistula nearly always requires surgical correction. An Anal fistula can be a very complex and difficult disease, therefore many surgical treatment options exist. Your surgeon will discuss the options appropriate for your individualized care.