CHAOS: A fetal autopsy report

Congenital high airway obstruction syndrome (CHAOS) is a rare congenital malformation, which results from deficient recanalization of the upper airways. Laryngeal atresia is the most common cause, other etiologies being trachea atresia, laryngeal or tracheal webs, subglottic stenosis, obstructing laryngeal cysts, and laryngeal or tracheal agenesis. There is decreased clearance of the fluid produced by fetal lungs due to obstruction leading to increased intratracheal pressure and thereby secondary proliferative lung growth. The heart becomes compressed in the midline due to hyperexpansion of the lungs causing elevated intrathoracic pressure, decreased venous return, and fetal cardiac failure. This sequence causes ascites, placento-megaly, and eventually hydrops fetalis. We present a case of antenatal diagnosis of a fetus with CHAOS corroborated by fetal autopsy.