Choanal atresia is the congenital absence or closure of the paired openings between the nasal cavity and the nasopharynx. Because this obstruction is complete, the neonate with choanal atresia becomes an obligatory nose breather. The condition can cause death by asphyxiation in the newborn.

The average incidence of choanal atresia is 0.82:10,000. Unilateral involvement occurs more frequently than the bilateral form by a ratio of about 2:1, with the right side being affected more often than the left. This condition affects females more frequently than males.

During the normal uterine developmental process, the nasal cavities extend posteriorly under the influence of the posteriorly directed fusion of the palatal processes. The membrane thins, separating the nasal cavities from the oral cavity. The two-layer membrane that consists of nasal and oral epithelia ruptures and forms the choanae. This occurs by the 38th developmental day. If this rupture fails to occur, choanal atresia is the result. The “preliminary” choanae are not in the same location as the definitive choanae, which are eventually located even more posteriorly.