Pyloric Stenosis

Pyloric stenosis is the thickening and narrowing of your baby’s pylorus, which is the muscular opening between their stomach and their small intestine. The full medical term for this condition is hypertrophic pyloric stenosis (HPS):

• Hypertrophic refers to hypertrophy, which means thickening.
• Pyloric refers to the pylorus.
• Stenosis means narrowing.

HPS causes projectile vomiting and can lead to dehydration in babies. Fortunately, surgery can repair this issue.

What happens in pyloric stenosis?

Your pylorus is a muscular sphincter (a muscle that opens and closes). It’s located at the end of your stomach, where your stomach meets your small intestine. Your pylorus contracts (closes) when your stomach is digesting food and liquid. It then relaxes (opens) to let food and liquid pass into your small intestine.

When the pyloric muscle is too thick, it narrows the passageway. Liquid and food can’t move from the stomach to the small intestine. A baby with pyloric stenosis often forcefully vomits since formula or breast milk can’t leave their stomach. Many babies have difficulty gaining weight because they have many episodes of vomiting.

How often do babies with pyloric stenosis vomit?

Babies with pyloric stenosis may vomit after every feeding or after just some feedings.

When does pyloric stenosis occur?

Babies usually aren’t born with pyloric stenosis. The thickening of their pylorus starts to happen in the weeks after birth.

Pyloric stenosis symptoms usually start when your baby is between 3 and 6 weeks old. But it can take up to five months for symptoms to become apparent. If you notice symptoms, talk to your baby’s healthcare provider. It’s best to treat HPS before your baby becomes dehydrated and undernourished.

Can older children get pyloric stenosis?

In rare cases, older children can get a pyloric obstruction — something blocking the passage through their pylorus. Usually, a peptic ulcer is the cause in older children. Sometimes, a rare disorder such as eosinophilic gastroenteritis, which inflames the stomach, can cause the condition.

How common is pyloric stenosis?

Pyloric stenosis affects 1 to 3.5 out of every 1,000 newborns. It’s the most frequent condition requiring surgery in infants.