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Printed at: 04:45:00 / 18-09-2021

Anal Fissure

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What are an anal fissure and a chronic anal fissure?

An anal fissure is a small tear of the skin of the anus. Although the tear is small, it can be very painful because the anus is very sensitive. The pain tends to be worse when you pass faeces (sometimes called stools or motions) and for an hour or so after passing faeces. Often an anal fissure will bleed a little. You may notice blood after you pass faeces. The blood is usually bright red, stains the toilet tissue, but soon stops.

Anal fissures are common in both adults and children. They are not usually serious, but they are sore and can be distressing, particularly in children. In most cases the fissure heals within 1 – 2 weeks or so, just like any other small cut of the skin. Treatment at first aims to ease the pain and keep the faeces soft until the fissure heals. A fissure that lasts more than six weeks is called a chronic anal fissure. (Chronic means persistent.)

What causes an anal fissure?

Common causes
Most anal fissures are thought to be due to passing large or hard faeces when you are constipated. The rim of the anus may stretch and tear slightly. Spasm (tightening) of the muscle around the anus (the sphincter) may play a part in causing the tear. In about 1 in 10 cases, the fissure occurs during childbirth. Sometimes an anal fissure occurs if you have bad diarrhoea. Anal fissures and other conditions In a minority of cases, a fissure occurs as part of another condition. For example, as a complication of Crohn’s disease or an anal herpes infection. In these cases you will have other symptoms and problems as well. These types of fissures are not dealt with further in this leaflet.

Why do some anal fissures not heal and become ‘chronic’?
It is thought that the muscle tone (pressure) around the anus is quite high in people with a chronic anal fissure. If the muscle tone around the anus is high, the blood supply to the anus is reduced. This can affect how well the tear heals.

What is the treatment for an acute anal fissure?
In most cases the fissure will heal within a week or so, just like any other small cut or tear to the skin. Treatment aims to ease the pain and keep the faeces soft whilst the fissure heals.

Easing Pain and Discomfort
• Warm baths are soothing, and may help the anus to relax which may ease the pain.
• A cream or ointment that contains an anaesthetic may help to ease the pain. You should use this only for short periods at a time (5-7 days). If you use it for longer, the anaesthetic may irritate or sensitise the skin around the anus. You can get one on prescription. You can also buy some of these products at pharmacies without a prescription.
• Wash the anus carefully with water after you go to the toilet. Dry gently. Don’t use soap whilst it is sore as it may irritate.
• Painkillers such as paracetamol may help to ease the pain (but avoid codeine – see next page).

Preventing constipation and keeping faeces soft
If you keep the stools soft, and avoid getting constipated, it will help a fissure to heal and help to prevent it happening again. You can do this by the following:
• Eat plenty of fibre by eating plenty of fruit, vegetables, cereals, wholemeal bread, etc.
• Have lots to drink. Adults should aim to drink at least two litres (10-12 cups) of fluid per day. You will pass much of the fluid as urine, but some is passed out in the gut and softens the faeces. Most sorts of drink will do, but alcoholic drinks can be dehydrating and may not be so good.
• Fibre supplements. If a high fibre diet is not helping, you can take bran or other fibre supplements (‘bulking agents’) such as ispaghula, methylcellulose, orsterculia. You can buy these at pharmacies or get them on prescription. Methylcellulose also helps to soften faeces directly which makes them easier to pass.
• Toileting. Don’t ignore the feeling of needing the toilet to pass faeces. Some people suppress this feeling and put off going to the toilet until later. This may result in bigger and harder faeces forming that are more difficult to pass later.
• Avoid painkillers that contain codeine such as cocodamol, as they are a common cause of constipation. Paracetamol is preferable to ease the discomfort of a fissure.

What if the anal fissure does not heal?
An anal fissure will heal within 1-2 weeks in most cases, but may take longer to heal in some cases. A fissure lasting more than six weeks is called a chronic (persistent) anal fissure and needs further treatment – see further down.

Prevention of a further anal fissure
If you have had one anal fissure, after it has healed you have a higher than average chance of having another one at some time in the future. The best way to avoid a further fissure is not to become constipated by using the measures described above. That is, a high fibre diet, fluid, etc. Leaflets that list foods high in fibre are commonly available. Ask your practice nurse for one if you cannot obtain one.

What are the treatments for chronic anal fissure?
If you left a chronic anal fissure, there is a reasonable chance that it will heal on it’s own without any treatment, or just with warm baths and pain relief. Some, however, persist and treatment helps to heal the fissure as quickly as possible. Treatment of a chronic anal fissure aims to:

• Keep the faeces soft and easy to pass. See earlier section.
• Relax the tone or strength of the muscle around the anus. This allows a good blood flow and enables the fissure to heal as quickly as possible. This can be achieved using glyceryl trinitrate
ointment.

Glyceryl trinitrate ointment
If you apply glyceryl trinitrate (GTN) ointment to the anus, it relaxes the muscle around the anus (the anal sphincter). This allows the fissure to heal better. It may also ease the pain very quickly.
About 7 in 10 people with a chronic anal fissure are cured with a course of GTN ointment. (About 5 in 10 will heal in this time with the ‘traditional’ treatment of regular warm baths and using an anaesthetic cream for pain relief.) Therefore, the chance of cure by using GTN is better than the traditional method.

Some points to note if you use GTN ointment include the following:
• There is only one branded product of GTN ointment that is used to treat anal tissue. It is called Rectogesic and is only available on prescription. Rectogesic contains 0.4% GTN. You should use this exactly as described on the leaflet that comes with the packet. For example:
• A standard dose is 2.5 cm squeezed out of the tube. (A measuring line comes with the product to measure 2.5 cm of ointment.)
• You squeeze a dose of ointment onto a finger (which you can cover beforehand with cling film or similar). You then place the ointment just inside the anus.
• The ointment is used every 12 hours for a full 6-8 weeks even if the pain goes much sooner. This is because it often takes 6-8 weeks of treatment for the fissure to heal fully, even if the pain has gone.
• The product leaflet gives details of who should not use the ointment and what side-effects that may occur.
• Up to 6 in 10 people have a headache after applying GTN ointment as the GTN gets into the bloodstream. The headache usually goes within 30 minutes. Painkillers such as paracetamol will help if a headache occurs. If headaches are troublesome, try using a smaller amount of ointment for a few days, and then gradually increase the amount back to normal over several days.
• Another tip if you get bad headaches is to rub a smaller amount of ointment (a pea sized amount) around the rim of your anus rather than inserting the full amount into the anus. GTN is absorbed more into the bloodstream from the thin skin inside the anus. Using a smaller dose of ointment just on the rim of the anus may avoid side-effects (but may not be as effective as using the full dose inserted into the anus.)
• For people aged 12-18, and for people who develop bad side-effects such as headache, your doctor may advise a lower strength of GTN ointment. There is no commercially available ointment that is a lower than 0.4% strength. However, a pharmacist can make up a 0.2% strength of ointment by diluting a stronger 2% preparation which is used for other medical conditions.

Other medicines
Other medicines may be useful to relax the anal sphincter muscle and quicken healing. Anoheal® (Diltiazem 2%) has a similar effect to GTN ointment. It may cause skin itching which usually disappears after a few days.

Botox® (botulism toxin)
The injection of Botox® (botulism toxin) into the anal sphincter muscle relaxes the muscle by temporarily paralysing it. This is the way Botox® works to smooth out facial wrinkles. By relaxing the muscle, there is an increase in blood flow to the fissure which increases the chance of the fissure healing. There is an approximately 70% chance of the fissure healing with Botox®. It is usually injected under a general anaesthetic as a day case procedure. It occasionally has the complication of causing minor incontinence of gas (wind). The effect of Botox® lasts about 3 months and the injection can be repeated.

Surgery
Surgery is an option if all other treatment fails. It is also an option if you have recurring fissures. The success rate with surgery is very high – at least 9 in 10 cases are cured. The usual operation is to make a small cut in the muscle around the anus (‘lateral sphincterotomy’). This permanently relaxes the muscle of the sphincter around the anus and allows the fissure to heal. This is a minor operation which is usually done as a day-case under general anaesthetic.

However, surgery may cause complications. After this operation, up to 1 in 3 people have poor control of gas (wind), and a small number have soiling of underclothes or mild bowel incontinence.

Will it happen again?
Some people seem prone to recurring anal fissures. Up to 3 in 10 people who are successfully treated with GTN ointment will have one or more recurrences at some time in the future. It is thought that these people have an ongoing higher than average pressure (tone) of the muscle around the anus. They are more likely to tear the rim of the anus if it is stretched. (So, avoiding constipation is important.) However, a further course of GTN ointment can be used to help to heal any future fissure. Surgery may be an option if you have frequent recurrence.