Kids Health Info

Pyloric stenosis - an overview

  • Pyloric stenosis is a condition that affects the digestive system. It can cause your baby to vomit forcefully.

    Pyloric stenosis happens when muscles in a part of the lower stomach, called the pylorus, become bigger. The pylorus is like a tube through which food passes from the stomach into the small intestine (bowel). When the pylorus is enlarged, food cannot empty out of the stomach because there is not enough room for the food to go through the pylorus into the bowel.

    This causes symptoms such as vomiting, and leads to  weight loss or poor weight gain because the body cannot get the nutrients it needs from food.

    Pyloric stenosis occurs in babies when they are between two and six weeks of age, and an operation is needed to fix the problem. It is more likely to occur in first born male children of Caucasian families, particularly if a parent has had pyloric stenosis.

    Signs and symptoms

    • Vomiting which becomes progressively more forceful and may be projectile.
    • Often hungry after vomiting.
    • Weight loss or poor weight gain. 

    Diarrhoea is not usually a symptom of pyloric stenosis.

    Dehydration is a very serious risk, especially in young babiesIf your child has persistent vomiting, see your doctor immediately.


    Your child may need to be admitted to hospital for  frequent blood tests to check their electrolyte levels and have treatment for dehydration.

    This is done by putting an intravenous drip (IV drip) into your child's vein and giving fluids through it. At this stage they do not need to eat or drink.

    If your child keeps vomiting after they have stopped eating, they may need to have a tiny plastic tube inserted through their nose and down in to their stomach. Nurses will use this to remove the contents of the stomach to stop the vomiting.

    Once the child is rehydrated and their electrolytes are at a normal level, an operation is done to fix the problem.

    Your child can usually start eating and drinking within six hours of the operation, although some children will continue to vomit for several days.

    Once the problem has been repaired by surgery, it is unusual for pyloric stenosis to come back again.

    Key points to remember

    • Pyloric stenosis usually shows in infants aged between two and six weeks.
    • Symptoms include forceful vomiting that becomes worse, the child being hungry after the vomiting and  weight loss or poor weight gains.
    • An operation is needed to correct pyloric stenosis.
    • It is unusual for the problem to recur after the operation.

    For more information

     Developed by RCH Dept of Gastroenterology. First published December 2007. Updated November 2010

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This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital, Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.