Hypertrophic pyloric stenosis

[Zipporah Schumaker]

Hypertrophic pyloric stenosis is blockage of the passage out of the stomach due to thickening (hypertrophy) of the muscle at the junction between the stomach and the intestines.

The thickened muscle creates a partial blockage (obstruction) that interferes with the passage of stomach contents into the small intestine.
Infants feed well but vomit forcefully (projectile vomiting) shortly after eating and can become dehydrated and undernourished.
The diagnosis is based on results of an abdominal ultrasound.
Typically the problem is corrected by fluids given by vein (intravenously) and by minor surgery.

The pylorus is the muscular sphincter located where the stomach joins the first part of the small intestine (duodenum). Normally, the pylorus contracts to keep food in the stomach for digestion and relaxes to let the food out into the intestine. For reasons that doctors do not fully understand, the pylorus becomes thickened and sometimes closes off (called stenosis), blocking material from leaving the stomach. This blockage usually occurs in the first month or two of life.