ABSTRACT
Posterior choanal atresia is a condition in which the opening at the back of the nostril into the nasopharynx or post-nasal space fails to develop normally. In the normal subject there is a wide passage on either side, as described in Chapter 30. Failure of normal embryological development can lead to the posterior nasal aperture being closed, either by membrane or by bone of variable thickness. The condition occurs in approximately 1 in 60,000 live births. Approximately 40% of cases involve both sides.
