An anal fissure, fissure in Ano or rectal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on toilet paper and undergarments, or sometimes in the toilet. If acute they are painful after defecation,but with chronic fissures, pain intensity is often less.
Anal fissures usually extend from the anal opening and are usually located posteriorly in the midline, probably because of the relatively unsupported nature and poor perfusion of the anal wall in that location. Fissure depth may be superficial or sometimes down to the underlying sphincter muscle. Untreated fissures develop a hood like skin tag (sentinel piles) which cover the fissure and cause discomfort,
Superficial or shallow anal fissures look much like a paper cut, and may be hard to detect upon visual inspection, they will generally self-heal within a couple of weeks. However, some anal fissures become chronic and deep and will not heal. The most common cause of non-healing is spasming of the internal anal sphincter muscle which results in impaired blood supply to the anal mucosa.