During attempted inspiration, the tongue is pulled to the palate, and obstruction of the oral airway results. Vigorous respiratory efforts produce marked chest retraction. Then the crying stops, the mouth closes, and the cycle of obstruction is repeated. It has become clear over the years that serial dilatations are needed to maintain patency of the choanae. The average rate of choanal atresia is 0.82 per 10,000 individuals.
Unilateral atresia occurs more frequently on the right side.
A slightly increased risk exists in twins. Maternal age or parity does not increase the frequency of occurrence. Five percent of patients have monogenic syndromes or conditions. Choanal atresia occurs equally across races. The nasal cavities extend posteriorly during development under the influence of the posteriorly directed fusion of the palatal processes.