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congenital absence or closure of a normal body opening or tubular structure; see also obstruction. adj., adj atret´ic.
anal atresia (atresia a´ni) imperforate anus.
1. congenital absence of the aortic orifice.
2. absence or closure of the aortic orifice, a rare congenital anomaly in which the left ventricle is hypoplastic, so that oxygenated blood passes from the left into the right atrium through a septal defect, and the mixed venous and arterial blood passes from the pulmonary artery to the aorta by way of a patent ductus arteriosus.
aural atresia absence of closure of the auditory canal.
biliary atresia congenital obliteration or hypoplasia of one or more components of the bile ducts, resulting in persistent jaundice and liver damage.
choanal atresia blockage of the posterior nares. When the blockage is bilateral in a newborn, it produces acute respiratory distress because neonates are nose-breathers. Diagnosis is confirmed if a catheter cannot be passed through the nares. Until surgery is done to relieve the obstruction, insertion of an airway may be necessary.
esophageal atresia congenital lack of continuity of the esophagus, commonly accompanied by tracheoesophageal fistula, and characterized by accumulations of mucus in the nasopharynx, gagging, vomiting when fed, cyanosis, and dyspnea. Treatment should begin with suction of the upper esophageal pouch, followed by surgical repair by esophageal anastomosis and division of the fistula as soon as the infant's general condition permits.
follicular atresia (atresia folli´culi) the normal death of the ovarian follicle when unfertilized.
laryngeal atresia congenital lack of the normal opening into the larynx.
mitral atresia congenital obliteration of the mitral orifice; it is associated with hypoplastic left heart syndrome and transposition of great vessels.
prepyloric atresia congenital membranous obstruction of the gastric outlet, characterized by vomiting of gastric contents only. Called also pyloric atresia.
pulmonary atresia congenital severe narrowing or obstruction of the pulmonary orifice, with cardiomegaly, reduced pulmonary vascularity, and right ventricular atrophy. It is usually associated with tetralogy of fallot, transposition of great vessels, or other cardiovascular anomalies.
pyloric atresia prepyloric atresia.
tricuspid atresia absence of the tricuspid orifice, circulation being made possible by an atrial septal defect.
urethral atresia imperforation of the urethra.
a normal process affecting the primordial ovarian follicles in which death of the oocyte results in cystic degeneration followed by cicatricial closure.