Pyloric Stenosis

What is pyloric stenosis?

Pyloric stenosis is when the lower part of the stomach (called the pylorus) is too narrow for milk to pass through into the small intestine. Normally, the muscle at the end of the stomach contracts to keep food in the stomach and the muscle relaxes to let food out of the stomach. In pyloric stenosis, the muscle is too big and doesn't relax well. This happens to babies between 2 weeks and 2 months of age. It is also called infantile hypertrophic pyloric stenosis or gastric outlet obstruction.

What is the cause?

The cause of this condition is not known. Pyloric stenosis is more likely to occur in firstborn male infants. It also tends to run in families. Hormones from the mother may lead to the condition. It may be that the thickening of the muscle is a type of allergic reaction.

There may be problems with the way the body uses nitric oxide, a chemical that tells the pylorus muscle to relax. This could make the muscle tight almost all the time and cause it to get larger and thicker.

What are the symptoms?

Symptoms of pyloric stenosis generally begin around 3 weeks of age. They include:

  • vomiting
    • usually mild at first
    • gets more forceful within 30 minutes after feeding
    • projectile vomiting (breast milk or formula is ejected forcefully from the mouth in an arc, sometimes over a distance of several feet
  • constipation, small stools, green diarrhea, or stools with mucus in them
  • failure to gain weight or weight loss
  • being able to see waves in the infant's belly after eating
  • stomach pain or fullness after eating.

How is it diagnosed?

The healthcare provider will ask about your child's medical history and recent symptoms. It is very helpful if you can describe the vomiting.

Your baby will probably have a blood test. An ultrasound of the baby's abdomen may be done. A barium study may be done. The baby swallows a small amount of a chalky liquid (barium), and then special X-rays are taken.

How is it treated?

The baby will need surgery, called a pyloromyotomy. The surgeon cuts the tight muscle between the stomach and small intestine that is causing the problem. This loosens the muscle so food will be able to pass easily into the small intestine. Babies can usually eat shortly after the surgery.

When should I call my child's healthcare provider?

Call your child's provider if your baby has:

  • vomiting that lasts more than 6 hours
  • poor weight gain or weight loss
  • a fever greater than 101°F (38.3°C)
  • few or no stools for 1 or 2 days
  • signs of dehydration such as such as no urine in over 8 hours, sunken "soft spot" on the head, no tears when crying
  • jaundice (yellowing of the skin or eyes).
Developed by RelayHealth.
Published by RelayHealth.
Last modified: 2010-06-25
Last reviewed: 2010-03-02
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
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