Congenital high airway obstruction syndrome (CHAOS): discussing the role and limits of prenatal diagnosis starting from a single-center case series

Abstract

Objectives: we aimed to report our experience about congenital high airway obstruction syndrome (CHAOS) that is a rare and fatal congenital anomaly; laryngeal atresia is the most frequent cause. Sonographic findings are enlarged echogenic lungs, dilated trachea, and ascites. Methods: we performed a single-center case series analysis collecting antenatally through ultrasound examination, and some of them confirmed by autopsy. Results: we report six cases of CHAOS diagnosed by antenatal ultrasonography between 2007 and 2013. Conclusion: to date literature provides very few individual case reports. This work describes typical sonographic findings of this syndrome and it underlines the importance of early prenatal diagnosis to improve prognosis thought an ex utero intrapartum treatment, that seems to be the only chance of survival for the affected fetus.Key words: congenital high airway obstruction, prenatal diagnosis, diagnosis, prognosis. IntroductionCongenital high airway obstruction syndrome (CHAOS) is an extremely rare congenital anomaly, caused by laryngeal or tracheal atresia, tracheal stenosis, obstructing laryngeal cysts and obstructing tumors of the oropharynx and the cervical region, or rarely by compression from a double aortic arch (1). Laryngeal atresia seems to be the most frequent cause (2). In these cases, an outflow obstruction of the fetal lung fluid leads to pulmonary hyperplasia. Prenatal ultrasound findings are very characteristic and include lungs symmetrically enlarged and highly echogenic, dilated and fluid-filled trachea and bronchi, inverted hemidiaphragms (3). The heart appears small compared with the enlarged lungs and positioned towards the midline of the thorax due to compression by the lungs. Fetal ascites is often present and sometimes hydrops. MethodsWe report our experience of six cases of CHAOS, diagnosed antenatally through ultrasound examination, and some of them confirmed by autopsy.

Congenital high airway obstruction with tracheoesophageal fistula

“…The diaphragm flattens or inverts according to the severity of the process, and mediastinal shift with decreased venous return and disturbance of cardiac function eventually leads to heart failure and hydrops. [12,13] That is why CHAOS always has similar clinical manifestations.…”