Pyloric stenosis

Pyloric stenosis

When a baby has pyloric stenosis, forceful or projectile vomiting soon after feeds is usually the first symptom. If your baby has pyloric stenosis, they will need surgery.

Key points to remember

  • the pylorus is the passage that connects the lower part of the stomach to the small intestine
  • all food leaving the stomach has to go through the pylorus
  • when a baby has pyloric stenosis, the muscles in the pylorus have become too thick to allow food or milk to pass through it
  • forceful or projectile vomiting soon after feeds is usually the first symptom
  • if your baby has pyloric stenosis, they will need surgery
  • before surgery, your baby's dehydration needs to be fully corrected by intravenous fluids

What is it?

Pyloric stenosis (also called infantile hypertrophic pyloric stenosis or gastric outlet obstruction) is a narrowing of the pylorus – the passage leading from the stomach to the small intestine. When a baby has pyloric stenosis, the muscles in the pylorus have become too thick to allow food or milk to pass through it. This usually happens in the first 6 weeks after birth. For some some diagrams of the stomach and pylorus, see the Patient.co.uk website.

What causes it?

It is not known what causes the thickening and enlargement of the muscles in the pylorus.

What puts my child at risk of getting it?

Pyloric stenosis affects more boys than girls (85:15) and tends to run in families.

What are the signs and symptoms?

  • vomiting:
    • persistent vomiting of feeds, usually within 30 minutes of a feed
    • vomiting may be so forceful that the vomit can be projected one metre out of the mouth (projectile vomiting)
    • the vomit is usually yellow, the colour of curdled milk
    • occasionally, the vomit may have small brown specks of old blood in it
    • despite the vomiting babies are usually keen to feed (because they are starving)
  • being miserable:
    • because they remain hungry
    • from stomach cramps which may be painful
  • failure to gain weight or weight loss
  • fewer, smaller stools
  • dehydration:
    • dry mouth and tongue
    • fewer wet nappies or not passing as much urine as usual
    • unusual sleepiness, difficult to rouse (lethargic)
    • sunken eyes
    • the soft spot on the top of the head (fontanelle) is more sunken than normal
  • sometimes you can see ripples or waves across the stomach (abdomen) after a feed – these are muscle contractions (peristalsis) as the stomach tries to empty into the small intestine

When should I seek help?

Pyloric stenosis requires immediate treatment.

You should go to your doctor or after-hours medical centre if your baby has signs or symptoms suggestive of pyloric stenosis. Do not delay as young babies who are not able to feed normally can become more ill very quickly.

How is it diagnosed?

Your doctor needs accurate information about your baby’s symptoms, including:

  • patterns of feeding and vomiting
  • colour of the vomit
  • any weight loss or failure to gain weight

Your doctor will also try to feel a mass or lump (which is the thickened pylorus) in your baby’s stomach.

Investigations or tests, if necessary, may include the following:

  • a test feed – your baby may be given a small feed and then watched for a few hours
  • an ultrasound of your baby’s abdomen – this may show the thickened pyloric muscle
  • a barium meal – this is a special x-ray. Your baby is given a small amount of chalky liquid (barium) and then an x-ray of the abdomen shows the passage of the barium through the gut. Any blockage or narrowing can be seen
  • blood tests – if the vomiting has been severe and prolonged, dehydration and loss of electrolytes in the blood may have occurred

What treatment is required?

The treatment for pyloric stenosis is an operation called a pyloromyotomy.

This is performed by a team that usually includes a paediatric surgeon and a paediatric anaesthetist.

A pyloromyotomy can be done using one of three techniques:

  1. open operation – a small cut is made directly over where the pylorus is
  2. umbilical approach – the cut is in the tummy button (umbilicus) itself
  3. ‘key hole’ surgery – three tiny cuts are made

In all the operations, the surgeon then cuts through and spreads the thickened and enlarged muscles of the pylorus, which relieves the blockage (obstruction).

What happens to my child before the operation?

  • your child will not be allowed to eat or drink anything
  • your child will need to have an intravenous drip put into their hand or arm before the operation. Children with pyloric stenosis usually have abnormal levels of several important substances in their blood. These must be corrected before any operation. This usually takes several hours and can even take a day or longer
  • your child’s surgical team will discuss your child’s operation with you, and any other treatment needed; you will have the opportunity to ask questions or make comments at this time

What happens to my child after the operation?

Your baby will be brought back to the ward to recover. They will be given medicines through the intravenous drip to help relieve any pain.

For the first few hours, your baby will continue to have fluids through the drip. This will give the stomach time to start healing. After a few hours, your child will be able to start feeding. You will have to start with small amounts.

Your baby may still vomit some of the feed but this won’t be forceful or projectile vomiting as before. The vomits or spills will decrease over several days. You will be able to take your baby home once they are feeding normally.

How can I care for my child at home after discharge?

Continue to give your baby pain relief as advised by the doctor as their tummy may still be sore for a day or two.

Handle your child normally.

Your surgeon will tell you when you can start giving your baby a bath. Until then, you can give your baby washes with a cloth. Usually you can bath your child any time after the surgery.

Keep an eye on the wound. Take your child to your GP (general practitioner) for urgent review if you notice any signs of infection:

  • increased redness around the wound
  • increased oozing or pus coming from the wound
  • a temperature
  • swelling around the wound
  • your baby stops feeding

You will need to take your baby back to the hospital to be reviewed as an outpatient.

Complications of the operation

All operations carry some degree of risk: bleeding during and after the surgery and the risks of anaesthesia. There is a small chance of damage occurring to the delicate lining of the bowel, but this is usually recognised and fixed at the time of surgery. Pyloric stenosis can reoccur but this is rare.

This page last reviewed 19 March 2015.
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