MONDO_0012155 (choanal atresia) (CA) is a congenital anomaly of the posterior nasal airway characterized by the obstruction of one (unilateral) or both (bilateral) choanal aperture(s), with clinical manifestations ranging from acute respiratory distress to chronic nasal obstruction. Also known as: atresia of nares, imperforate nares, posterior choanal atresia.