Pyloric Stenosis: A-to-Z Guide from Diagnosis to Treatment to Prevention

In pyloric stenosis, the pyloric valve is too tight to permit stomach contents to pass through easily. Pyloric stenosis is more common in boys than girls.

“The spit up is getting worse and worse. Now it’s after every feed. I think it may even be projectile vomiting, but I’m not sure.”

Many babies spit up. A few gradually eject larger quantities of breast milk or formula until they are barely keeping anything down. This can be caused by a condition called pyloric stenosis, in which the muscular valve at the base of the stomach grows too tight to allow milk to pass.

What is it?

The gastrointestinal system is a long convoluted tube extending from the mouth, through the body, down to the anus. During development a portion of the tube may not form. This is called atresia. In esophageal atresia, for example, a section of the esophagus is missing. More commonly, a portion of the tube is too narrow. This is called stenosis. In pyloric stenosis, for example, the pyloric valve is too tight to permit stomach contents to pass through easily.

Who gets it?

Pyloric stenosis can occur in boys or girls, but it is much more common in boys, especially in firstborn boys. It is also more common in those with Northern European ancestry and in those with type B or type O blood. It seems to cluster in babies whose mothers have recently taken erythromycin.

Pyloric stenosis can run in families. It is also more common in some medical syndromes, such as Turner syndrome and Cornelia de Lange syndrome.

What are the symptoms?

The main symptom of pyloric stenosis is vomiting that gets progressively worse. The vomiting usually happens immediately after a feeding and usually happens with each feed. Often, the child remains hungry and would like to feed again after vomiting. Classically, the vomiting becomes ‘projectile,’ shooting far out from the baby’s mouth. Dehydration can progress quickly. Some develop jaundice.

Is it contagious?


How long does it last?

Most children with pyloric stenosis are not born with it, but vomiting usually starts at around 3 to 5 weeks of age as the pylorus tightens. Pyloric stenosis can start earlier or months later.

The condition generally continues until treated.

How is it diagnosed?

The diagnosis is suspected based on the story and the physical exam (sometimes the pylorus feels like an olive in the belly). Imaging studies such as ultrasounds are often used to confirm the diagnosis.

How is it treated?

In the United States, pyloric stenosis is corrected with surgery – with excellent results. Over time, doctors have found that open surgery (with an incision along the abdominal wall) may sometimes be avoided through the use of laparoscopic surgery (where surgeons make several tiny incisions to use several thin instruments to perform the surgery). In either case, the baby is usually rehydrated before the operation.

A fascinating article in the October 2001 issue of Indian Pediatrics describes what happened when 52 babies were treated with atropine instead. Atropine is an ancient medicine that can relax spasms in smooth muscles. Used incorrectly, it can be a poison. But it is also a powerful antidote (in nerve gas attacks, for instance). In fifty of the babies in the study (96.2 percent), the pyloric stenosis resolved with the medicine alone. The other 2 babies improved, but still needed surgery. No side effects interrupted the treatment in any of the babies. Atropine or some other medicine may prove to be a safe, effective, cheap, non-invasive alternative to surgery.

How can it be prevented?

Usually, pyloric stenosis cannot be prevented.

Avoiding erythromycin during the final stages of pregnancy and early days of nursing may prevent some cases.

Projectile vomiting, Hypertrophic pyloric stenosis

Last medical review on: October 29, 2013
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Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.
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