What are anal fissures and fistulas?
An anal fissure is a tear in the lining of the anus or the skin around it. An anal fistula is an abnormal track or channel from the anus that opens onto the skin surrounding the anus.
What causes anal fissures and fistulas and who is at risk?
Frequently, no cause is found for the development of an anal fissure. The most commonly associated condition is constipation.
Anal fistulas are associated with a number of conditions that result in inflammation of the digestive tract. These include ulcerative colitis and Crohn's disease (see separate Factsheet). More commonly, however, fistulas are caused by infection and abscess (collection of pus) in one of the glands near to the anus. Multiple anal fissures may also be associated with these conditions.
What are the common symptoms and complications of anal fissures and fistulas? Sudden and severe pain in or around the anus is the characteristic symptom of an anal fissure. The pain often occurs during or shortly after the passage of a hard stool, but may also occur spontaneously.
After that, the pain occurs now and then and is severe, sharp and often shooting in nature; it is often made worse by a bowel movement. As a result, sufferers often avoid opening their bowels, which makes the constipation worse and prevents the fissure from healing. The condition is frequently associated with something called a 'sentinel pile'. This pile, or haemorrhoid, is a small vein that has dropped down from inside the anus to lie outside. It may bleed from time to time and a streak of bright red blood on the toilet paper may be seen.
Anal fistula is most commonly associated with an abscess near the anus, which gives rise to pain in or around the anus that may be dull and throbbing. The abscess releases pus, which may be blood-stained and soil the underclothes. The formation of a fistula results in the often continuous seepage of pus or sometimes a more thin and watery fluid, again often streaked with blood, from the anus. If the underlying abscess is large enough it may cause a fever and a feeling of being generally unwell.
If a fistula has been caused by an inflammatory bowel disease, such as ulcerative colitis or Crohn's disease, other symptoms of the disease may be present. These may include diarrhea, abdominal pains, fever, loss of appetite, weight loss, nausea and vomiting.
What is the treatment for anal fissures and fistulas?
Self-care action plan
Avoiding constipation by eating a diet rich in fibre (including plenty of fruit and vegetables) helps to prevent anal fissures from occurring. Such a diet also helps the healing process.
If diet alone is insufficient to control constipation, a number of medicines can be used, many of which are available as over-the-counter preparations from a pharmacist with no need for a prescription. These include lactulose, taken as a liquid, and tablets such as senna. Creams or ointments that contain pain-killing local anaesthetic agents are very useful at relieving the pain of anal fissures. Relief of the pain reduces the spasm in the muscles of the anus, which often prevents the fissure from healing.
If all the above measures fail, a variety of operations is available for the treatment of anal fissures. These include stretching of the anus, which is carried out under general anaesthetic (during which you will be asleep) and although normally performed as a day case, may require you to stay in hospital overnight. This procedure results in temporary weakening of the muscles around the anus, relieving the spasm and allowing healing to occur. Alternatively, a 'sphincterotomy' may be performed. This, again, is carried out under a general anaesthetic and involves cutting some of the muscle fibres around the anus. A chronic (long-term) fissure that does not respond to the above treatments often has to be cut out and then sewn up with stitches.
If an abscess is the cause of an anal fistula, it can only be treated surgically. The operation involves cutting into the abscess and draining the pus. If a fistula is present it will also need to be tackled surgically. This operation involves cutting into the fistula and 'laying it open' to allow healing to occur. This will involve a stay in hospital.
More rarely, when the fistula is caused by an associated inflammatory disease of the bowel, the particular disease often also requires specific treatment. This may involve taking steroid tablets to reduce the inflammation but if severe, surgery may also be required.
If you do have an operation for an anal fissure or fistula, you will be given instructions as to what to do when you get home. This is likely to include information about the importance of having a daily bath, how to avoid constipation, and when you should return to the doctor for a follow-up.
Relaxation therapy, the Alexander technique, yoga and tai-chi may help to relieve the stress and the underlying increase in muscle tension associated with the pain of an anal fissure, and may help to promote healing. These techniques may also promote a sense of well-being, which may be useful in such chronic painful conditions.
What is the outcome of anal fissures and fistulas?
Anal fissure is usually harmless and heals on its own, although it can be a very painful condition. Complete recovery is usual, and often occurs spontaneously; only rarely is surgery required.
Anal fistula, although rarely a serious condition, often requires surgical treatment, but again complete recovery is usual.