Normally, food passes easily from the stomach into the first part of the small intestine through a valve called the pylorus. With pyloric stenosis, the muscles of the pylorus are thickened. This prevents the stomach from emptying into the small intestine.
The cause of the thickening is unknown. Genes may play a role, since children of parents who had pyloric stenosis are more likely to have this condition.
Pyloric stenosis occurs most often in infants younger than 6 months. It is more common in boys than in girls.
Treatment for pyloric stenosis involves surgery to widen the pylorus. The surgery is called pyloromyotomy.
If putting the infant to sleep for surgery is not safe, a device called an endoscope with a tiny balloon at the end is used. The balloon is inflated to widen the pylorus.
In infants who cannot have surgery, tube feeding or medicine to relax the pylorus is tried.