Prenatal ultrasonography findings of fetus with congenital high airway obstruction (chaos): A case report and review of literature

Abstract

Congenital high airway obstruction syndrome (CHAOS) is an extremely rare life-threatening condition. The sonographic findings are very characteristic. Generally the diagnosis is made with the 4-chamber view of the fetal heart. Typically, both lungs appear severely enlarged and highly echogenic. The heart points towards the midline of the thorax. Fetal ascites is determined commonly on ultrasound examination. A case of CHAOS, diagnosed antenatally via ultrasound is reported here.

Congenital High Airway Obstruction Syndrome (CHAOS): No Intervention, No Survival—A Case Report and Literature Review

“…Laryngeal/tracheal atresia is a rare congenital anomaly that takes place by deficient recanalization of the upper airways at 9-10 weeks of embryological development leading to a clinical spectrum defined as congenital high airway obstruction syndrome (CHAOS) [1][2][3][4]8].…”

“…Normally, the fluid secreted by fetal lung is absorbed through the tracheobronchial tree [1,4]. However, in the case of airway obstruction, this fluid cannot be appropriately drained and keeps on accumulating in the fetal lungs which results in a gradual rise in intratracheal pressure and leads to hyper expansion and abnormal development of the lungs [1][2][3][4]. The hyper expanded lungs compress the heart, great veins, and diaphragm.…”

“…Congenital high airway obstruction syndrome (CHAOS) is a rare life-threatening disorder caused by complete or nearcomplete obstruction of the fetal upper airway [1][2][3][4][5][6][7]. It was first described by Hedrick in the late 1900s [1,2,4,8]. Laryngeal atresia or stenosis is the commonest cause of CHAOS [1,2,4,7,9].…”

“…Bilateral enlarged hyperechoic lungs, flattened or inverted leaflets of the diaphragm, and dilated fluid-filled tracheobronchial tree are the typical antenatal sonographic findings. Fetal ascites and nonimmune hydrops are the other associated findings of this syndrome [1][2][3][4][5][6]10]. Accurate prenatal recognition of this lethal entity is becoming an important issue, as currently available management options, particularly, ex utero intrapartum treatment (EXIT), have a promising favorable neonatal outcome [1,3,4,11,12].…”

“…It was first described by Hedrick in the late 1900s [ 1 , 2 , 4 , 8 ]. Laryngeal atresia or stenosis is the commonest cause of CHAOS [ 1 , 2 , 4 , 7 , 9 ]. CHAOS is usually a fatal condition that is not compatible with life and leads to a stillbirth or early neonatal death if not recognized in the antenatal period [ 1 , 2 , 4 , 7 ].…”