Absence of a normal opening or normally patent lumen.clausura; [G. a- priv. + tresis, a hole]
anal a. , a. a´ni congenital absence of an anal opening due to the presence of a membranous septum (persistence of the cloacal membrane) or to complete absence of the anal canal.imperforate anus (1) , proctatresia;
aortic a. congenital absence of the normal valvular orifice into the aorta.
biliary a. a. of the major bile ducts, causing cholestasis and jaundice, which does not become apparent until several days after birth; periportal fibrosis develops and leads to cirrhosis, with proliferation of small bile ducts unless these are also atretic; giant cell transformation of hepatic cells also occurs. Cf. neonatal hepatitis.
bronchial a. severe focal narrowing or obliteration of a segmental or lobar bronchus, usually associated with distal air trapping.
choanal a. congenital failure of one or both choanae to open owing to failure of the bucconasa membrane to rupture.
esophageal a. congenital failure of the full esophageal lumen to develop; commonly associated with tracheoesophageal fistula.
a. follic´uli a normal process affecting the primordial ovarian follicles in which death of the ovum results in cystic degeneration followed by cicatricial closure.
intestinal a. an obliteration of the lumen of the small intestine, with the ileum involved in 50% of cases and the jejunum and duodenum next in frequency; most frequent cause of intestinal obstruction in the newborn; etiology may be related to a failure of recanalization during early development or to some impairment of blood supply during intrauterine life.
a. i´ridis congenital absence of the pupillary opening.atretopsia;
laryngeal a. congenital failure of the laryngeal opening to develop, resulting in partial or total obstruction at or just above or below the glottis.
pulmonary a. congenital absence of the pulmonary valve orifice.
tricuspid a. congenital lack of the tricuspid orifice.
vaginal a. congenital or acquired imperforation or occlusion of the vagina, or adhesion of the walls of the vagina.ankylocolpos, colpatresia;
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