What causes Hirschsprung's disease?

In Hirschsprung's disease, a section of the gut (bowel) does not work properly. Usually it is a small section towards the very end of the bowel which is affected. It is not known why this is the case, but it seems to be a failure of development of the nerves in one part of the bowel while the baby is in the womb.

The defect may be inherited through genes passed on from parents. It is more common in children who have a family member who has been affected by Hirschsprung's disease. It is sometimes associated with other genetic conditions such as syndrome de Down. There is no obvious genetic cause in many cases, however.

The nerves control the muscles of the inside wall of the bowel tube. Without the nerves, the muscles do not contract. Without the squeezing effect of the muscle contractions, poo is not moved along the bowel, so it gets stuck.

Hirschsprung's disease is a condition which is present from birth. Usually this malfunction of the bowel causes problems immediately, so the condition becomes apparent in the first few days of life. So it is most commonly diagnosed in newborn babies. However, if a very small section of the bowel is affected, symptoms may be less severe. If this is the case, the diagnosis may not be made until the children are a little bit older. Very rarely it is diagnosed in adults.

Hirschsprung's disease is rare. About 1 in 5,000 babies have the condition. As mentioned above, it is more common in babies with Down's syndrome. About 1 in 11 babies with Hirschsprung's disease also have Down's syndrome, and babies with Down's syndrome have about 40 times the chance of having Hirschsprung's disease. There are also associations with other rare genetic conditions.

The symptoms from Hirschsprung's disease come from poo getting stuck, and the effects that brings. So there is de la constipation - ie no poo is passed, or it is passed with extreme difficulty. That leads to tummy swelling et tummy pain. In many cases, this is a problem within the first day or two after the baby is born. They may not pass any poo at all after being born. Some babies with Hirschsprung's disease do, however, start off by passing some dark green new baby poo (meconium), but then start having problems a few days, weeks or months later. If the blockage becomes very severe, the baby may start bringing up (vomiting) a green or brown fluid.

If the condition is not severe enough to be apparent early on, the symptoms may not be so obvious. An older child with Hirschsprung's disease may have long-standing de la constipation, tiredness, tummy pains and poor growth. It may be difficult to get them out of nappies as they may have incontinence due to an overflow of poo leaking round the blockage.

If Hirschsprung's disease is not diagnosed, the first sign of it may be a complication called enterocolitis. This is an infection of the guts which is very serious. If not treated quickly, it can lead on to life-threatening complications such as leaking of the bowel wall (perforation) or septicémie. Symptoms of enterocolitis include a high temperature (fever), tummy pain and horrible-smelling diarrhoea, which sometimes contains blood.

A tummy (abdominal) radiographie usually shows there is a blockage. It shows loops of swollen guts. A blood test may be done to check for infection (enterocolitis).

In order to make the diagnosis, a biopsy is needed from the very lower end of the bowel (rectum). A biopsy is a procedure in which a small sample of tissue is taken from the affected area and examined under a microscope. If the diagnosis is Hirschsprung's disease, it will be apparent that the normal nerve cells are not present. Often a anesthésie générale will be needed to perform this test.

In older children or adults, other tests are sometimes used. These include an X-ray with a contrast substance (called a barium enema) or tests of the bowel muscles (anal manometry).

The treatment for Hirschsprung's disease is an operation to remove the part of the gut which is not working. The normal gut is then re-connected. Sometimes this can't be done at the same time, in which case a temporary stoma is formed during the operation. A stoma is an opening in the tummy wall which allows stool to pass directly into a pouch worn on the body. In time, another operation is done to connect the ends of the bowel inside the tummy so that the stoma is no longer needed. It will depend on how old your baby or child is, and how unwell they are. Your specialists will advise on the best course of action and will explain exactly what it involves.

Sometimes if a baby is too unwell for an operation, in the short term they can be treated with bowel washouts to clear the poo. The operation will be needed at some stage however.

If Hirschsprung's disease is diagnosed and treated promptly, the outlook (prognosis) is good. The operation is usually very successful. As with any operation, however, there are risks, and your specialist will explain these to you. There is a small chance that there will be complications of the anaesthetic or the operation. After recovery, most children will have no further problems, although toilet training may take longer than usual. However, about 1 in 10 will have ongoing problems with constipation. A very few will have long-standing problems controlling their poo and be incontinent.

The most serious complication is infection of the guts (enterocolitis) and this can occur even some years after the operation. Seek urgent medical advice if your child has symptoms of a tummy bug, particularly any of the following:

• Blood in the poo.

• Horrible smelling diarrhoea.

• Une température élevée (fièvre).

• Tummy pain.

• A swollen tummy.