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anal fissure

Friday 30 March 2012

Anal fissures are common post-traumatic lesions, typically located posteriorly in the midline.

An anal fissure is a break or tear in the skin of the anal canal.

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.


The incidence of anal fissures is around 1 in 350 adults.

They occur equally commonly in men and women and most often occur in young adults aged 15 to 40.

Clinical synopsis

Anal fissures may be noticed by bright red anal bleeding on the toilet paper, sometimes in the toilet.

If acute they may cause severe periodic pain after defecation but with chronic fissures pain intensity is often less.


Most anal fissures are caused by stretching of the anal mucosa beyond its capability.

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. The result is a non-healing ulcer, which may become infected by fecal bacteria.

In adults, fissures may be caused by constipation, the passing of large, hard stools, or by prolonged diarrhea as well as anal sex.

In older adults, anal fissures may be caused by decreased blood flow to the area.

Other common causes of anal fissures include:
- childbirth trauma in women
- Crohn’s disease
- poor toileting in young children.

See also

- anal fistula