Atresia (z1589)

Atresia (from the Greek a- negative part, and tresis-opening), the congenital absence or underdevelopment of various natural openings in the body; e.g., A. of the rectum - absence of the anal opening, A. of the vagina - absence of an exit from the vaginal canal to the perineum, etc. More rarely, A. denotes acquired conditions that have resulted in the obliteration (see) of natural openings; e.g., A. of the esophagus after ulcerative inflammation due to poisoning by a caustic liquid. Congenital A., which may also be of inflammatory origin, primarily affect the intestinal tube. Depending on their location, A. either render the subject non-viable (e.g., A. of the aorta) or cause severe suffering (e.g., A. of the vagina), which can only be eliminated by surgical means. A. develop predominantly in areas where the formation processes of various tubes, openings, or ducts are relatively complex (anus, duodenum near the ampulla of Vater, aorta at the entrance of the ductus arteriosus, etc.). For A. of individual organs, see the respective organs.