Congenital High Airway Obstruction Syndrome (CHAOS)?A Rare Fetal Malformation- Diagnosis on Antenatal Ultrasonography

Congenital high airway obstruction syndrome (CHAOS) is the obstruction of the fetal upper airways, which may be partial or complete. It is important to diagnose it antenatally as it is uniformly lethal and leads to stillbirth or death shortly after delivery. Antenatal diagnosis is made by identifying echogenic and enlarged lungs, dilated bronchi, inverted /flattened diaphragm and ascites on ultrasound. We present a rare case of congenital high airway obstruction, diagnosed on antenatal ultrasonography at 18 weeks of gestation.