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Anal fissure
Published by Bupa's Health Information Team
November 2003
An anal fissure is a tear in the skin around the opening of the anus. It can cause sharp pain, especially when opening the bowels. Anal fissure is thought to be a common disorder for which many people do not seek medical advice. It can be easily confused with haemorrhoids (piles).
Symptoms
Sudden and severe pain in or around the anus is the main symptom of an anal fissure. The pain often occurs during or shortly after a bowel movement, but may also occur at other times. This pain can be severe - and is often described as like passing razor blades. As a result, a fissure sufferer is likely to dread opening their bowels.
An anal fissure may cause a "sentinel pile". This is a little tag of skin that develops on the edge of the anus where the fissure is. It may leave a streak of bright red blood on the toilet paper or drops of blood in the toilet bowel. A sentinel pile is not a haemorrhoid.
Most anal fissures are at the rear of the anal opening - in line with the cleft of the buttocks. A fissure can also occasionally be to the front or sides of the anus.
Anal fissures occur most commonly in young adults.
 Anal fissure
What causes anal fissures?
Frequently, no cause is found for an anal fissure. However, it is commonly linked to constipation, where straining on hard stools can tear the skin of the anus.
The internal anal sphincter (see diagram, above) is thought to play a key role in the development of an anal fissure. This is one of two muscles that control the opening of the anus. Both muscles need to relax in order to pass a stool. Unlike the exterior anal sphincter, which can be tensed or relaxed voluntarily, there is no voluntary control of the internal sphincter. Because of the pain of a fissure, the internal anal sphincter may go into spasm - causing a raised pressure within the anus.
This excess pressure makes it harder to pass a stool, making constipation worse, and contributing to a vicious circle. The spasm of the internal anal sphincter can also restrict the blood supply to the anal skin, which reduces its ability to heal.
Acute and chronic anal fissures
Anal fissures can be divided into those that have occurred quite recently - an acute fissure, or one that has failed to heal for some time - a chronic fissure.
An acute fissure looks like a fresh tear in the skin. With a chronic fissure, the walls of the tear become thickened. An examining doctor may be able to see the white fibres of the internal anal sphincter at the base of the tear.
Diagnosis
If you have symptoms of an anal fissure that do not improve within a couple of weeks, it is worth seeing your GP for advice and to rule out other conditions.
The doctor will listen to your description of symptoms and will probably want to know about your bowel habit. It may be too uncomfortable to perform a detailed examination, but he or she will want to have a look at the anal area too.
Treatment
Lifestyle changes
Changes to diet and lifestyle will help to encourage healing of a fissure. The main aim is to try and avoid constipation, so that stools are smaller and softer.
This can be achieved by eating a diet that is rich in fibre, including plenty of fruit, vegetables and wholegrain cereals such as brown rice, bread and pasta. You should also aim to drink enough water-based drinks so that your urine is no darker than pale yellow.
Taking a regular supplement of bulk-forming laxative (eg Fybogel) or a laxative that softens the stool (eg lactulose syrup) will help the healing process and prevent further tears.
Sitting in a warm bath after using the toilet may also relieve the spasm and bring some relief from the discomfort.
If your fissure has not healed despite these lifestyle changes, or if you are worried about it, you should see your doctor. If you have blood in your stool (rather than some spotting on toilet paper or in the bowel) or have recently experienced altered bowel habits or have been losing weight, another problem may be responsible for your symptoms and you should seek medical advice promptly.
Medicines
Creams or ointments that contain local anaesthetics (eg lidocaine) or steroids (eg hydrocortisone) can be useful in relieving the pain and inflammation, and consequently the spasm, of an anal fissure. Your doctor may prescribe these in conjunction with advice about avoiding constipation and, possibly, laxatives.
A number of new medical approaches to anal fissure have been introduced recently, although these are generally only prescribed by a hospital specialist. This is generally either a gastroenterologist or a colorectal surgeon.
Some of these treatments are based on medicines originally developed for treating heart conditions and high blood pressure, and are not officially approved (licensed) for treating anal fissure. They work by relaxing the muscle of the internal anal sphincter. This reduces the spasm and improves the blood flow to the anus. This helps the fissure heal. Ointments of glyceryl trinitrate and diltiazem, and ointment or tablets of nifedipine may be prescribed. Side-effects, particularly with glyceryl trinitrate, can include a headache.
An injection of botulinum toxin (Botox) is used by some specialists. It temporarily paralyses part of the sphincter, reducing spasm and so reduces the pressure in the anus and improves the blood flow.
Surgery
The aim of surgery is similar to that of medicines - to relieve the excessive pressure within the anal canal. This is done by cutting the internal anal sphincter in an operation called a lateral sphincterotomy, or by stretching it with an anal dilatation. These procedures are carried out in hospital under general anaesthetic. They are usually performed as a day case, without the need for an overnight stay. The treatment is generally effective at healing the fissure. However some degree of incontinence or an inability to control wind may result although this may improve with time.
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