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Pyloric stenosis

  • Definition

    Pyloric stenosis is a narrowing of the pylorus, the opening from the stomach into the small intestine.


    Alternative Names

    Congenital hypertrophic pyloric stenosis; Hypertrophic pyloric stenosis; Gastric outlet obstruction


    Causes, incidence, and risk factors

    Normally, food passes easily from the stomach into the duodenum (the first part of the small intestine) through a valve called the pylorus. In pyloric stenosis, the muscles of the pylorus are thickened. This thickening prevents the stomach from emptying into the small intestine.

    The cause of the thickening is unknown, although genetic factors may play a role. Children of parents who had pyloric stenosis are more likely to have this problem.

    Pyloric stenosis occurs more often in boys than in girls, and is rare in children older than 6 months. The condition is usually diagnosed by the time a child is 6 months old.