Atresia

Congenital absence or severe narrowing of a body opening or tubular organ, due to a failure of development in the uterus. Examples are biliary atresia, in which the bile duct between the liver and duodenum are absent; oesophageal atresia, in which the oesophagus comes to a blind end; and anal atresia (see anus, imperforate), in which the anal canal is shut off. Most forms of atresia require surgical correction early in life.