What is an anal fissure?

An anal fissure is a split in the skin at the opening of the anus, which leaves exposed some of the muscle fibres of the anal canal. Pain results from the recurrent opening of the wound when the bowels are opened, and it is often accompanied by bleeding. In addition, the inner circle of muscle in the anal canal (called the internal sphincter) goes into spasm: this makes the pain worse and can prevent healing. Anal fissures are different from haemorrhoids and have no relationship with cancer.

What are the symptoms of an anal fissure?

Pain on passing faeces, which might persist for minutes or hours afterwards. The pain is typically sharp and knife-like rather than an ache.

Bright-red bleeding when you pass faeces.

If the fissure is long-standing, a skin tag at the site of the fissure can develop.

What are the treatments for an anal fissure?

General measures:

A high-fibre diet: By eating a high-fibre diet and drinking plenty of water (6–10 glasses a day), you should aim to keep your motions soft. Sometimes a fibre supplement (such a Fybogel) can help.

Sitz baths: An 'ordinary' 15-minute bath but in water as warm as you can tolerate several times daily (or as often as you require) can be very soothing and provide several hours of pain relief.

What is glyceryl trinitrate (GTN) ointment?

GTN is a relatively new treatment for anal fissures, which acts by relaxing the internal sphincter muscle. This provides pain relief by relieving spasm. It also improves the blood supply to the fissure, which promotes healing in a majority of patients. Although GTN is not yet officially licensed for treating fissures, it is widely accepted by colorectal surgeons to be a valuable alternative to surgery, which has previously been the standard practice. GTN is formulated as a 0.2% ointment, which can be applied three times a day to the skin around the anus and (if possible) a little inside. The only significant side effect of GTN is that it might cause a headache. If there is no relief of symptoms during a four-week period, then there is little advantage in continuing this form of treatment.

What kind of surgery can be performed for an anal fissure?

The most commonly used operation to treat anal fissures is called an internal sphincterotomy. It involves a part of the internal sphincter muscle being cut, which relieves the spasm of the muscle, stops the pain and allows the fissure to heal. Occasionally a polyp can develop at the inside edge of a long-standing fissure, and this can be removed at the same time. It is not usually necessary to remove or suture the fissure itself. The operation is very effective, but carries a small risk of some change in your ability to control wind from the back passage; in most cases, this problem will resolve completely, but in a small proportion of people, it can be permanent.


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