Narrowing of the PYLORUS, the muscular exit from the STOMACH. It is usually the result of a pyloric ulcer or cancer near the exit of the stomach. Food is delayed when passing from the stomach to the duodenum and vomiting occurs. The stomach may become distended and peristalsis (muscular movement) may be seen through the abdominal wall. Unless surgically treated the patient will steadily deteriorate, losing weight, becoming dehydrated and developing ALKALOSIS.
A related condition, congenital hypertrophic pyloric stenosis, occurs in babies (commonly boys) about 3–5 weeks old, and surgery produces a complete cure.