Pylorus is the name given to the area in which the stomach opens into intestine and pyloric stenosis is shrinkage of area of pylorus. The food we eat passes into the stomach and enters the small intestine by a valve or opening called pylorus. When the muscles in the pylorus get thickened it prevents the passage of food flow into the intestine resulting in a condition called pyloric stenosis.
The exact cause for this disease is still unknown. Genetic play a part in this disease since children inherit this disorder from their parents very often.