Condition Basics

What is pyloric stenosis?

Pyloric stenosis is a problem with a baby's stomach that causes forceful vomiting. It happens when the baby's pylorus, which connects the stomach and the small intestine, swells and thickens. This can keep food from moving into the intestine.

A baby may get pyloric stenosis anytime between birth and 3 months of age. It rarely happens in babies older than 3 months. It usually starts about 3 to 6 weeks after birth. If your baby was born early (premature), symptoms may start later.

What causes it?

Experts don't know what causes pyloric stenosis. It may be passed down through families.

What are the symptoms?

A baby with pyloric stenosis may:

• Vomit soon after a feeding.
• Have a full, swollen upper belly after a feeding.
• Act fussy and hungry a lot of the time.
• Have fewer and harder stools than normal.
• Pass less urine than normal.

Vomiting usually starts gradually. As the pylorus becomes tighter, the vomiting may become more frequent and more forceful.

As the vomiting continues, your baby may:

• Lose weight.
• Become dehydrated.
• Be sleepier than normal and very fussy when awake.

How is it diagnosed?

Your doctor will do a physical examination and ask about your baby's symptoms. If your baby has pyloric stenosis, the doctor may be able to feel a small lump in the upper part of the belly.

In some cases your baby may need imaging tests, such as an upper GI (gastrointestinal) series or an abdominal ultrasound. Your baby also may need blood tests to see if he or she is dehydrated.

How is pyloric stenosis treated?

Pyloric stenosis is treated with surgery to widen the opening between the stomach and the small intestine. Surgery rarely causes problems, and almost all babies recover completely. After surgery, your baby probably won't get pyloric stenosis again.

Your baby likely will be ready to go home within 2 days after surgery. Being involved in your baby's care while he or she is in the hospital may help you feel more comfortable when you take your baby home. Talk with the doctor about how to feed your baby and what to expect. It's normal to feel nervous, but don't be afraid to hold and handle your baby.