Definition of Atresia

Atresia: Absence of a normal opening or failure of a structure to be tubular.

Atresia can affect many structures in the body, including:

• Anal atresia -- congenital absence of a hole at the bottom end of the intestine. Also called imperforate anus.
• Aortic atresia -- congenital absence of the normal valvular opening into the aorta.
• Biliary atresia -- absence of the major bile ducts, causing jaundice.
• Choanal atresia -- congenital failure of one or both nasal passages to open.
• Esophageal atresia -- a birth defect in which part of esophagus is not hollow.
• Intestinal atresia -- obliteration of the hollow of the small intestine, involving the ileum (50% of cases) or the jejunum or duodenum.
• Laryngeal atresia -- congenital failure of the laryngeal opening to develop, resulting in partial or total obstruction at or just above or below the glottis.
• Pulmonary atresia -- congenital absence of the pulmonary valve opening in the heart.
• Tricuspid atresia -- congenital lack of the tricuspid valve opening.
• Vaginal atresia -- congenital occlusion of the vagina or subsequence adhesion (sticking together) of the walls of the vagina occluding it.