Atypical presentation of congenital high airway obstruction sequence (CHAOS) masked by tracheo-esophageal fistula in a case of vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities (VACT

Congenital high airway obstruction syndrome traditionally presents with a predictable constellation of prenatal ultrasound findings: hyperinflated echogenic lungs with dilated obstructed airway, inverted diaphragms, and fetal ascites and/or hydrops [ 1 ]. These features result from the entrapment of fetal lung fluid, which causes massive lung distension and increased intratracheal and intrathoracic pressure, leading to secondary ascites and hydrops via venous system compression. Severe polyhydramnios often develops because the lung expansion compresses the esophagus, impairing fetal swallowing [ 2 ]. However, where a tracheo-esophageal fistula masks these classic sonographic signs by allowing fetal lung fluid to decompress into the digestive tract, the lungs will appear normal on prenatal ultrasound and hydrops does not develop, making antenatal diagnosis nearly impossible [ 3 , 4 ]. This report details a fatal case of CHAOS with V ertebral defects, A nal atresia, C ardiac defects, T racheo- E sophageal fistula, R enal anomalies, and L imb abnormalities (VACTERL) association, where the absence of typical indicators of CHAOS on prenatal imaging precluded life-saving interventions.