atresia and stenosis
Absence (atresia), usually congenital, or narrowing (stenosis) of almost any normal body cavity or passage. The more important include atresia of the anus, esophagus, aortic arch, heart valves, and urinary passages; and stenosis of the intestine, urinary passages, pyloric valve (stomach outlet), and heart valves. Most must be surgically corrected soon after birth.
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