Pyloric stenosis

Published by Bupa's Health Information Team, April 2010.

This factsheet is for parents of children with pyloric stenosis, or people who would like information about it.

Pyloric stenosis is a condition that develops in babies in the first couple of months after they are born. It means that part of the baby's digestive system has narrowed, so milk can't get through to be digested.

About pyloric stenosis

The pylorus is the section of your baby's digestive system between his or her stomach and small bowel. Pyloric stenosis occurs when the muscle in this area thickens, causing the pylorus to become narrower. As a result of this narrowing, milk can't get through to be digested.

Pyloric stenosis affects about one baby in every 400. The symptoms usually appear between three and six weeks after a baby is born.

Pyloric stenosis is about four times more common in boys than in girls, particularly in first-borns. It's less likely to develop in babies who are breastfed.

Symptoms of pyloric stenosis

The first symptom that you notice is likely to be your baby vomiting small amounts of milk after feeding. At first, this may not be any more than usual. However, over a few days this will get worse and your baby won't be able to keep any milk down. The vomiting will become more severe and powerful. This is called projectile vomiting and it may be so forceful that it travels some distance out of your baby's mouth. The milk that your baby vomits may be yellow or curdled and unpleasant smelling as it will have mixed with acid in his or her stomach.

Other symptoms that your baby may have include:

• constipation
• being hungry all the time
• weight loss
• lack of energy

If your baby has these symptoms, see your GP. It's important that your baby receives treatment for pyloric stenosis, otherwise he or she may become seriously dehydrated. Your baby also won't be able to put on weight as he or she won't be absorbing any nutrients from the milk being drunk.

Causes of pyloric stenosis

The exact reasons why your baby may develop pyloric stenosis aren't fully understood at present. However, there is evidence that the condition runs in families, particularly from mothers to their sons. Researchers are carrying out studies to try to identify the gene or genes that are involved in this process.

Diagnosis of pyloric stenosis

Your GP will ask about your baby's symptoms and examine him or her. During the examination, your GP will feel to see if there is a small hard lump on the right-hand side of your baby's stomach. This is called the 'olive test' because the thickened pylorus feels a bit like an olive. It's especially noticeable when your baby is feeding.

Your GP may ask you to give your baby a feed so that he or she can observe and examine your baby during this and any vomiting that occurs afterwards. During the feed, it may be possible to see the muscles around your baby's stomach moving from side to side as they try to push milk through the pylorus.

Your GP will want to rule out other conditions that could be causing your baby's symptoms, such as an infection, overfeeding or the possibility that your baby has a milk allergy.

It's likely that your GP will refer you to a specialist. He or she will do further tests including:

• blood tests
• a barium meal - this involves your baby swallowing a drink containing barium (a substance that shows up on X-rays); X-ray images of your baby's abdomen (tummy) then show the inside of his or her bowel more clearly
• an ultrasound scan - this uses sound waves to produce an image of the inside of your baby's abdomen and will show the thickened pylorus muscle

Treatment of pyloric stenosis

Your baby will need to have an operation called a pyloromyotomy. This is sometimes referred to as a Ramstedt's pyloromyotomy or a Ramstedt operation. A surgeon will split your baby's pylorus muscle and spread it open. This allows your baby's pylorus to widen and allow milk through.

The operation is carried out under general anaesthetic. This means that your baby will be asleep during the operation and will feel no pain. The operation takes about half an hour.

Before the operation, your baby will probably be put on a drip to give him or her fluids. This helps to rehydrate your baby and return his or her blood to a healthy state.

Your baby will have a tube put up his or her nose and down the oesophagus (the pipe that goes from the mouth to the stomach). This gets rid of any liquid still in his or her stomach and will be removed after the operation.

After the operation your baby will probably have to stay in hospital for a few days. It's recommended that you wait at least four hours after the operation before feeding your baby to try to reduce the risk of vomiting. He or she may still vomit a bit at first, but it probably won't be as serious as before.

You will be able to take your baby home once he or she is feeding well and putting on weight. Your baby is likely to make a full recovery and have no further problems.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.