ATRESIA AND STENOSIS

absence, usually congenital, of a normal bodily passage or cavity (atresia) or narrowing of a normal passage (stenosis). Most such malformations must be surgically corrected soon after birth. Almost any cavity or passage may be affected; some of the more important of these disorders are as follows. Anal atresia (imperforate anus) is a malformation of the intestinal tract (about one out of every 6,000 births in the United States) with varying degrees of congenital absence of the anus and lower end of the bowel. It is often associated with other anomalies of development. Surgery is required to produce a functional anal sphincter. Esophageal atresia is a disorder in which only part of the esophagus develops and often connects with the trachea. Surgery may repair the defect. Bile-duct atresia is a condition that is always accompanied by severe jaundice and that limits the person's capacity to digest fatty foods. Survival for a few years is possible, and in a small but increasing number of cases, surgery is effective. Intestinal atresia occurs about twice as frequently as intestinal stenosis; there is a total incidence of one out of every 3,000 births, with the ileum (the final section of the small intestine) being most affected. Vomiting and complete obstruction dictate early surgery. Aortic-arch and heart-valve atresias cause serious difficulty in early life but can sometimes be repaired by surgery. Ureteric and urethral atresias and stenoses cause distension of the urinary tract above the obstruction, with impairment of kidney function and often infection. Pyloric stenosis is a spasmodic narrowing of the opening between the stomach and the duodenum. It is a relatively common cause of illness in newborns, occurring four times more often in males than in females and more frequently in whites than in blacks. The defect requires prompt surgical care. Aortic, pulmonary, and heart-valve stenoses all cause mild to severe circulatory difficulty in early life but can be repaired by surgery. See also agenesis.