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Pyloric stenosis

Pyloric stenosis usually develops in babies in the first couple of months after they are born.

Your baby will have symptoms that include projectile vomiting and weight loss. The condition can be treated with an operation and most babies get better quickly and have no further problems.

  • About pyloric stenosis
  • Symptoms
  • Causes
  • Diagnosis
  • Treatment
  • Sources

About pyloric stenosis

Pyloric stenosis affects one to two babies in every 500. The symptoms appear between about three and six weeks after birth, although rarely it can develop some months later.

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

It's important that your baby receives treatment for the condition, as otherwise he/she may become seriously dehydrated. Your baby also won't be able to put on weight as he/she isn't absorbing any nutrients from the milk being drunk.


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 down any milk. The vomiting will become more severe and powerful. This is called projectile vomiting and may be so forceful that it travels some distance out of your baby's mouth. The milk that is vomited may be yellow or curdled and unpleasant smelling as it will have mixed with acid from the stomach.

Other symptoms that your baby may have include:

  • dehydration
  • constipation
  • being hungry all the time
  • weight loss
  • lethargy

It's important to see your GP if your baby has these symptoms as without treatment he/she may become very dehydrated.


The exact reasons why your baby may develop pyloric stenosis aren't fully understood at present. However, there is evidence that it 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.

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


Your GP will ask about your baby's symptoms and examine him/her. Your GP may also ask about your baby's medical history. 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 he or she can observe and examine your baby during this and also see any vomiting that happens 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 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 swallowing a drink containing barium (a substance which shows up on X-rays); X-ray images of your baby's abdomen (tummy) then show the inside of the 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 up the thickened pylorus muscle


At the moment, the only way to treat pyloric stenosis is with surgery.


Your baby will need to have an operation called a pyloromyotomy. This is also sometimes called Ramstedt's pyloromyotomy or a Ramstedt operation. The procedure is carried out under general anaesthetic. This means that your baby will be asleep during the operation and 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/her fluids. These help to rehydrate your baby and return the blood to a healthy state.

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

After the operation your baby will probably have to stay in hospital for a few days. You will be able to start feeding your baby again after a few hours. He/she may still vomit a bit at first, but it probably won't be as serious as before. 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.

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


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  • Infantile hypertrophic pyloric stenosis. Surgical Tutor. www.surgical-tutor.org.uk, accessed 16 January 2008
  • Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2006:858-859
  • Pyloric stenosis. UCL Institute of Child Health, Great Ormond Street Hospital for Sick Children NHS Trust. www.ich.ucl.ac.uk, accessed 16 January 2008
  • Longmore M, Wilkinson IB, Rajagopalan S. Oxford Handbook of Clinical Medicine. 6th ed. Oxford: Oxford University Press, 2004:494
  • Common paediatric disorders. Royal College of Surgeons of Edinburgh. www.rcsed.ac.uk/eselect/sig2.htm, accessed 16 January 2008
  • Bilt J, Kramer W, Zee D, Bax N. Early feeding after laparoscopic pyloromyotomy: the pros and cons. Surg Endosc 2004; 18(5):746-748