choanal

Choanal is an anatomical term relating to the choanae, the two posterior openings that connect the nasal cavities with the nasopharynx. Each side contains a choana, yielding left and right openings through which air passes from the nasal passages to the throat. The choanae are essential for normal nasal airflow and develop as part of the palate and surrounding skull bones during embryology.

Congenital choanal atresia, the best-known condition involving the choanae, results from failure of recanalization of the nasal cavity during fetal development. It can be membranous, bony, or mixed. Bilateral atresia causes respiratory distress and cyclic cyanosis in newborns, because infants are obligate nasal breathers; symptoms may improve when crying as airflow shifts to the mouth. Unilateral atresia typically presents as chronic unilateral nasal obstruction or discharge. Choanal stenosis is a milder narrowing of the openings and may be difficult to distinguish clinically. Acquired obstruction of the choanae can occur with trauma, infection, polyps, or tumors.

Diagnosis relies on nasal endoscopy and imaging, usually CT, to delineate the anatomy and extent of obstruction. Treatment is surgical correction, commonly via transnasal endoscopic approaches, and may require stenting or revision in complex cases. Prognosis depends on the severity of the atresia and the presence of associated anomalies, such as those seen in CHARGE syndrome.