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a narrowing of the lumen of the pylorus, the sphincter of the stomach. In adults it results from cicatricial deformation caused by chemical burns of the stomach or peptic ulcers; it is also caused by tumors of the stomach and neighboring organs. In newborns, pylorostenosis is a congenital hypertrophy of the pyloric muscles. The disease is marked by disruption of the evacuation of the stomach contents into the duodenum that leads to dilatation of the stomach and disruption of digestion. Symptoms of pylorostenosis are a constant feeling of fullness in the stomach; projectile vomiting, which gives temporary relief; emaciation; and dehydration. X-ray examination reveals dilatation of the stomach and obstruction of the pylorus. The disease is treated surgically.