Congenital High Airway Obstruction – Case Report with Imaging Features

Congenital high airway obstruction syndrome (CHAOS) is a near fatal condition of multifactorial inheritance, due to the obstruction of the fetal upper airways, which may be partial or complete in which the fetus has a dilated trachea, enlarged echogenic lungs, an inverted or flattened diaphragm, and ascites. Prenatal recognition of the disease is quite important due to the recently described management options We report here a case of CHAOS due to laryngeal atresia diagnosed by antenatal ultrasonography at 19 weeks of gestation. We also briefly review the relevant literature with the associated management options. Case A 22-year-old primigravida woman was referred for routine second trimester antenatal ultrasound at 19 weeks of gestation. There was no history of consanguinity and the family history was unremarkable. Ultrasound examination revealed that the fetus had distinctly dilated trachea, bilateral enlarged hyperechoic lungs, inferiorly displaced and flattened diaphragms [Figure 1]. The heart was centrally placed and appeared to be compressed by the enlarged lungs and gross fetal ascites [Figure 2]. Increased nuchal thickness was also noted [Figure 3]. No other additional anomaly was found. Based on ultrasound examination, diagnosis of CHOAS due to laryngeal atresia was made. After thorough counselling and explaining the outcomes of this pregnancy the parents were convinced to undergo termination as this was incompatible with life and was also fitting the criteria for legal age of termination. Discussion Laryngeal atresia is a very rare congenital malformation which results due to nondevelopment of the 6 th branchial arch during embryogenesis resulting in a clinical spectrum defined as congenital high airway obstruction syndrome (CHAOS) [1,2] . This has been classified into three types by Smith and Bain: type 1There is complete atresia of the larynx with midline fusion of the arytenoid cartilages and intrinsic muscles; type 2 There is infra-glottic obstruction characterized by a dome-shaped cricoid cartilage obstructing the lumen; and type 3 in which there is occlusion of the anterior fibrous membrane and fusion of the arytenoid cartilages at the level of the vocal processes. [1] Normally during the course of pregnancy, the fluid secreted by fetal lung is absorbed through the tracheobronchial tree. www.jmscr.igmpublication.org Impact Factor 5.244 Index Copernicus Value: 83.27 ISSN (e)-2347-176x ISSN (p) 2455-0450 DOI: https://dx.doi.org/10.18535/jmscr/v4i11.25