As a congenital birth defect, pyloric stenosis is the name for a narrowing of the opening from the stomach to the small intestine. This opening is known as the pylorus, and “stenosis” refers to its narrowing.
The result is that food cannot move smoothly from the stomach to the initial part of the small intestine, known as the duodenum, since it must pass through a narrowed pylorus whose muscles have become thicker. Such thickened muscles make it difficult for the stomach to dispose of its contents by funneling them into the small intestine.



