Q40.0: Congenital hypertrophic pyloric stenosis

The pylorus is narrower than usual.

The stomach is located in the upper abdomen. The stomach has a curved shape, creating a big curve and a small notch. The stomach is made up of different sections. Food reaches the entrance to the stomach through the gullet (oesophagus). The food is then transported into the body of the stomach. The fundus of the stomach is located at the top of the stomach. Air often collects there. There is a small extension further down in the stomach. This is the section in front of the end of the stomach or pyloric orifice. There is a sphincter muscle, the pylorus, at the end of the stomach. The pylorus transports the food in portions into the small intestine.

The pylorus has narrowed because the circular sphincter muscle has changed. This type of change typically occurs in the first weeks after birth. But it may also be that the sphincter changed prior to the birth. The reasons for the disorder are not yet known. In some families more than one child has a changed sphincter in the pylorus. So it is believed that the disorder is hereditary. The disorder occurs more often in boys than girls.

If the sphincter is too narrow, it will be more difficult for food to get from the stomach into the intestine. The partially digested food backs up at the bottleneck. This can cause projectile vomiting. Abdominal pain may also result. If less food gets into the intestine, the body may absorb less nutrients and water. This can cause malnutrition. This can impair general physical development.