Overview of Pyloric Stenosis

Pyloric stenosis is a rare condition that occurs in infants younger than 6 months old. It is usually diagnosed when a baby is between 3 and 12 weeks of age.

The pylorus is an opening at the bottom of the stomach. The muscles around the pylorus expand and contract to allow food to pass into the small intestine. In pyloric stenosis, muscles (called the pyloric sphincter) or other tissues (e.g., mucosa, submucosa) around the opening are abnormally thick, narrowing the pylorus and interfering with digestion. Because food cannot pass through properly, it remains in the stomach. Eventually, the baby vomits, often quite forcefully, and is unable to keep any food down.

Pyloric stenosis is a medical emergency. The condition can be corrected quite easily with surgery, but the diagnosis must be made as soon as possible to prevent severe dehydration and malnutrition.

Incidence and Prevalence of Pyloric Stenosis

In the United States, pyloric stenosis affects approximately 2–4 out of 1,000 infants. The condition occurs more often in Caucasians than other races and is less frequent among children of mixed race. Boys are approximately 4 times more likely to have pyloric stenosis than girls. An estimated 30% of cases occur in first-born males.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 28 Aug 2008

Last Modified: 02 Jun 2011