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.

Bluish discoloration of the skin and mucosa due to poor circulation or inadequate oxygenation of arterial or capillary blood.