Anal Fissure


An anal fissure is a split in the skin of the anus, just at the opening to the outside. It is a common condition that is often caused by passing a hard stool, though it sometimes occurs after diarrhoea, following childbirth or in association with other conditions. In many patients there is no obvious cause for the fissure. In many patients, the anal sphincter will go into spasm (known as a ‘high pressure fissure’), and this can prevent healing. In others (‘low pressure fissure’) there is no spasm.


The most common symptom of a fissure is severe pain during and after passing stools. This pain may last just a few minutes at a time or several hours. Bright red rectal bleeding sometimes occurs. Itching can be a very troublesome symptom, especially at night. There may also be a tender tag at the bottom of the fissure known as a sentinel tag.


The diagnosis of an anal fissure can usually be made by a surgeon taking a detailed note of symptoms and performing a simple examination during your consultation. Occasionally, the surgeon may feel that the fissure is a sign of a more global problem with the pelvic floor and may recommend some diagnostic tests.


Many fissures heal spontaneously or with simple measures such as keeping stool soft by a combination of diet, hydration and a stool softeners such as Laxido or Fybogel (see Medication). Others do not heal and become chronic.

The usual initial treatment in this case is in the form of a medicinal paste, either glyceryl trinitrate (GTN; ‘Rectogesic’) or diltiazem (‘Anoheal’). These pastes are applied to the skin around the anus or just inside the anal canal itself. They relax the anus and promote blood supply to the area, thus promoting healing. It is important to complete the prescribed course (usually about six weeks) even if symptoms settle quickly. These drugs can have side effects; between a quarter and a half of patients using them suffer short-lasting headaches. It is safe to take simple pain killers to relieve headache in such cases. After a few days of continued use the headaches will ease off, so it is worthwhile persisting with the ointment.

If the fissure remains unhealed, injection of botulinum toxin into the anus can help by temporarily reducing the tone of the anal sphincter, removing spasm and allowing the fissure to heal. This can be combined with a fissurectomy, an operation in which the fissure is ‘cleaned up’ to remove skin tags and give a neat, clean wound which heals more easily. However low pressure fissures do not respond to this treatment, and in these cases an advancement flap may be required. This is where a small piece of healthy tissue is taken from the rectum or skin around the anus and ‘advanced’ to cover up the skin around the fissure.

We try to avoid carrying out the ‘internal sphincterotomy’ operation for anal fissure. In this procedure the internal anal sphincter is cut to prevent spasm and promote fissure healing. This causes permanent sphincter damage and can eventually lead to incontinence, particularly in females. However there may be a role for sphincterotomy in some people with persistent fissures, usually males, where the risk of incontinence is judged to be very low.

Please be advised that the information on this website is not a substitute for professional medical advice, diagnosis or treatment