Atresia is a condition in which an orifice or passage in the body is (usually abnormally) closed or absent.

Examples of atresia include:

  • Biliary atresia, a condition in newborns in which the common bile duct between the liver and the small intestine is blocked or absent.[1]
  • Choanal atresia, blockage of the back of the nasal passage, usually by abnormal bony or soft tissue.[2]
  • Esophageal atresia, which affects the alimentary tract and causes the esophagus to end before connecting normally to the stomach.[3]
  • Imperforate anus, malformation of the opening between the rectum and anus.[4]
  • Intestinal atresia, malformation of the intestine, usually resulting from a vascular accident in utero.[5]
  • Microtia, absence of the ear canal or failure of the canal to be tubular or fully formed[6] (can be related to Microtia, a congenital deformity of the pinna, or outer ear).
  • Ovarian follicle atresia, the degeneration and subsequent resorption of one or more immature ovarian follicles.[7]
  • Potter sequence, congenital decreased size of the kidney leading to absolutely no functionality of the kidney, usually related to a single kidney.
  • Pulmonary atresia, malformation of the pulmonary valve in which the valve orifice fails to develop.[8]
  • Renal agenesis, only having one kidney.
  • Tricuspid atresia, a form of congenital heart disease whereby there is a complete absence of the tricuspid valve, and consequently an absence of the right atrioventricular connection.[9]
  • Vaginal atresia, a congenital occlusion of the vagina or subsequent adhesion of the walls of the vagina, resulting in its occlusion.


  1. Zieve, David. "Biliary atresia". PubMed Health. Retrieved 11 September 2012.
  2. Zieve, David. "Choanal atresia". Pubmed Health. Retrieved 11 September 2012.
  3. Dugdale, David. "Esophageal atresia". PubMed Health. Retrieved 11 September 2012.
  4. Kaneshiro, Neil. "Imperforate Anus". PubMed Health. Retrieved 11 September 2012.
  5. "Intestinal atresia". Pedisurg. Retrieved 11 September 2012.
  6. Bonilla, Arthuro. "Microtia: Congenital ear deformity Institute". Congenital ear deformity Institute. Retrieved 11 September 2012.
  7. Kaipia, A.; Hsueh, A. J. W. (1997). "Regulation of Ovarian Follicle Atresia". Annual Review of Physiology. 59: 349–363. doi:10.1146/annurev.physiol.59.1.349. PMID 9074768.
  8. Schumacher, Kurt. "Pulmonary atresia". PubMed Health. Retrieved 11 September 2012.
  9. "Tricuspid atresia". PubMed Health. Retrieved 11 September 2012.
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