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Anal Fissure

About Anal Fissure

An anal fissure is a tear or ulcer in the anal skin just on the inside of the anal canal. The typical site is posterior (towards the tail bone), but may occur anteriorly.

What are the typical symptoms?

Typically the patient will experience discomfort or acute perianal pain, which is in the background nearly all of the time, but is exacerbated dramatically upon defecation. After defecation the pain tends to persist for an hour or so before fading to the usual discomfort. Associated with the pain is bleeding, once again with defecation. This is usually confined to the paper but occasionally can be seen in the toilet bowl. There may also be a small skin tag close by (otherwise known as a sentinel tag) that becomes swollen because of the associated inflammation. Because of the pain and bleeding many patients and even GP's mistake the diagnosis of a fissure for haemorrhoids. The notable difference is that the history is relatively short (a few weeks) and there is an absence of prolapse (swellings on the inside that come out with defecation).

What causes a fissure?

We're never quite sure of the exact cause of a fissure. A fairly constant finding is spasm of the sphincter muscle but why the sphincter muscle goes into spasm is unknown. Certain factors can initiate the spasm, in particular a bout of diarrhea or delivering a baby. The probable mechanism is that the sphincter muscle becomes so tight that it cuts off the blood supply to an area of skin just on the inside. Skin like everything else in the body has a blood supply and if you deny it of its blood supply it will die, resulting in a tear or ulcer. The putative mechanism is supported by the fact that treatment directed at reducing the sphincter spasm results in healing of the fissure.


It is important to confirm the diagnosis and to exclude more significant pathology. This is easily achieved by a simple inspection which can be done either by the G.P or a specialist Colorectal Surgeon. Once the diagnosis has been established, no special investigations are required.

Treatment Options

The options with regard to treatment rest between conservative or operation. All fissures will eventually heal by themselves and will do so once the sphincter muscle has decided to relax spontaneously. This can take several weeks or even months. No amount of applying local medicaments, and this includes Rectogesic, will make any difference to this process. Keeping the stool soft with a regular intake of fibre (and a fibre supplement as required) and the use of a stool softener such as Coloxyl will ease the discomfort on defecation but will not necessarily hasten healing. The only solution with regard to active treatment is a procedure called a sphincterotomy which is generally very successful.

Related Information

Read about Anal Sphincterotomy