Pyloric stenosis is a narrowing of the opening from the stomach to the small intestine. Normally, when you eat something, it goes down your esophagus, into your stomach where acids work on it to break down the food, and then into your small intestine. The pylorus is the end of the stomach; in pyloric stenosis, the pylorus gets very thick and squeezed together, and the food can’t get past it into the small intestine. No one knows why this happens – it happens before birth, and it happens more often in boys than in girls.

The symptoms appear several weeks after birth. They start with mild vomiting that gets progressively worse within a half hour after feeding. This sometimes is called projectile vomiting because the vomiting is very forceful. The baby may appear constantly hungry and may have loose, green stool. Sometimes, a wavelike action happens on the stomach before vomiting. The baby doesn’t gain weight and can become very dehydrated. Belching and signs of abdominal pain also may occur.

Surgery is needed to make the opening wider. Before surgery, the baby is admitted to the hospital and given intravenous fluids to make sure he or she is hydrated (has plenty of liquids). The surgery is called pyloromyotomy or pyloric stenosis repair.

The child receives general anesthesia, and the stomach is cleaned and covered. A small incision is made in the abdomen, and the surgeon cuts into the pyloric muscle to release the restriction. No tissue is removed, and the stomach lining is not opened. The pyloric muscle returns to normal size with time.

One or two days in the hospital usually is all that is required. Children recover very quickly and usually tolerate feedings about 12 hours after surgery. Most babies can go from clear liquids to formula about 36 hours after surgery. Vomiting one or two feedings within the first one or two days after surgery is not unusual. A small incision in your baby’s right upper abdomen will be covered with tape. A firm ridge may be felt there. Wait to bathe the baby in a tub until five days after surgery. Carefully pat dry the incision after sponge bathing.

As with all surgery, there is a risk with anesthesia and a risk of bleeding or infection. In addition, there is a small risk of puncturing the stomach during surgery.

For an appointment with a Washington University pediatric surgeon, call (314) 454-6022, Monday-Friday, 8 a.m.-5 p.m.