Pyloric Stenosis (also called Infantile Hypertrophic Pyloric Stenosis or Gastric Outlet Obstruction)


Condition Description

Pyloric stenosis is a condition of infants where there is an obstruction in the gastrointestinal tract at the lower end of the stomach due to enlargement of the pyloric valve (also called the pylorus). The pyloric valve regulates emptying of stomach contents into the intestine, and for an unknown reason it becomes enlarged during early weeks of life.

There are many theories about why this enlargement (hypertrophy) of the valve occurs, such as genetic predisposition, allergy or hormonal effects. However, no specific causes have been proven. Typically the babies begin to have forceful vomiting of their feedings in the second or third week of life. They will be very hungry right after vomiting. Persistent vomiting can quickly lead to dehydration and electrolyte imbalance, which can be life-threatening. Babies will fail to gain weight (or will lose weight). They become irritable and weak if this condition is not corrected.


Pyloric stenosis occurs in 1 of every 200-300 live births and is four times more common in males. It is the most common cause of intestinal obstruction in infants. It is rare in Asians, and it is 2 to 3 times more common in Caucasian compared to African American babies. Parents who have had pyloric stenosis have a 10-20% chance of having a child who also has pyloric stenosis. In identical twins, if one develops this condition, 80-90% of the time the other twin will also develop pyloric stenosis.

Common Associated Conditions

About 7% of babies will have other conditions such as intestinal malrotation, urinary tract obstruction, and esophageal atresia. However over 90% of babies will have no other conditions.

Short-term Treatment and Outcomes

Babies often need intravenous fluids initially to bring their hydration and electrolytes back to normal because of the frequent vomiting. Once they are stable and hydrated, surgery to cut partially through the pyloric valve and relieve the obstruction will very successfully correct this problem.

Long-term Treatment and Outcomes

Babies who are quickly diagnosed and taken to surgery promptly will have an excellent outcome. They will be in hospital for 1-2 days post-operatively and will need to gradually resume their feedings. However there should be no long-term treatment, and outcomes are excellent for this condition.

Common Complications

Complications are very few unless the baby is not diagnosed promptly or has some other associated problems.

Implications for Children's Development

Because this is fairly easily diagnosed and corrected, pyloric stenosis should have no long-term effects on children's development. The surgical scar is very small and typically the babies heal quickly and resume normal feedings, growth and activities very quickly.

For more information, including resources for parents and general information about pyloric stenosis, visit the following websites: