Anal Fissure

What is an Anal Fissure?

The anal canal is a narrow, tube-like structure, about 4cm long, that extends from the rectum (the lowest section of the intestine) to the anal opening. It passes through the anal sphincter, the circle of muscles which surrounds the anal orifice, and helps to keep the faeces in the rectum, until the person is ready to defecate. An anal fissure is an ulcer in the tissue lining the canal, just above the anal sphincter. These ulcers which are thin, elongated tears in the wall lining, are fairly common. Because the open raw tissue is subject to irritation, pain may occur during bowel movements. This discomfort may also irritate the sphincter muscles, causing them to go into spasm, which is even more painful than the fissure itself.

Causes of an Anal Fissure

An anal fissure is usually caused by the passage of hard or large faeces, which tear the tissue lining in the anal canal. This problem is often associated with persistent constipation. In other cases, a fissure can occur after anal surgery, or be secondary to proctitis (inflammation of tissue lining the rectum), due to a disorder such as Ulcerative Colitis, Crohn’s disease, or gonorrhoea. An anal fissure may also be caused, or worsened, by anal intercourse. An anal fissure usually begins as a minor scratch, which fails to heal because of repeated contractions and stretching of the anal orifice, and is made worse by the passing of large, hard faeces, the tear in the tissue lining can cause severe pain during and after bowel movements, and may become infected. An untreated fissure may deepen and its walls become inflamed and thickened. Some people with anal fissures may delay going to the toilet, for fear of the pain it will cause. However, such delay causes further drying and compacting of the faeces, making them more difficult to pass, thus worsening the condition.

Symptoms of an Anal Fissure

• Pain during or shortly after bowel movements, sometimes persisting for several hours
• Pain occurring when pressure is placed on the anal area, for example, when sitting on a hard chair
• Bleeding during or after bowel movements, usually seen as a small amount of bright red blood on faeces or toilet paper
• Tendency towards constipation

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