The pylorus is the connection between the stomach and the first part of the small intestine. Pyloric stenosis is a condition in which a baby’s pylorus gradually swells and thickens. This interferes with food entering the intestine and causes the baby to vomit most or all of his or her feedings.

To treat pyloric stenosis, a surgeon widens the channel between the stomach and the intestine. Pyloric stenosis does not usually occur again after a baby has been treated.