English

Abstract

Congenital high airway obstruction syndrome (CHAOS) results in a predictable constellation of findings: large echogenic lungs flattened or inverted diaphragms, dilated airways distal to the obstruction, and fetal ascites and/or hydrops. 1 The finding of CHAOS on prenatal ultrasound examination is diagnostic of complete or near-complete obstruction of the fetal upper airway, most likely caused by laryngeal atresia. A greater understanding of the natural history of CHAOS may permit improved prenatal and perinatal management. INTRODUCTION: Congenital chest malformations are rare, and may involve the lung parenchyma, bronchi, arterial supply, and venous drainage. They include congenital cystic adenomatoid malformation (CCAM), congenital diaphragmatic hernia (CDH), bronchopulmonary sequestration (BPS), congenital hydrothorax, and congenital lobar emphysema. Rarer entities include congenital high airway obstruction syndrome (CHAOS), congenital bronchogenic cyst, bronchial atresia, pulmonary Arterio Venous malformation (PAVM), congenital pulmonary lymphangiectasia, pulmo- nary hypoplasia-aplasia, mediastinal teratoma, and mediastinal lymphangioma.2 Sometimes there may be compromise in normal pulmonary development, causing hypoplastic lung formation. Pulmonary abnormalities are not mutually exclusive, since abnormalities frequently occur together as hybrid conditions. MATERIALS AND METHODS: Here we present a case of a fetus post-delivery found to have large hyperechoic lungs, flattened diaphragm and hydrops in the prenatal scan, which form a triad in the detection of CHAOS. A brief review of literature is discussed. CASE PRESENTATION: In our case we had a twenty six years old pregnant lady with twenty two weeks history of amenorrohea who had come for a routine antenatal scan. She was the mother of a two year old child which was born normally and was doing well. On antenatal ultrasound of the present pregnancy, the fetus was found to be of approximately twenty weeks gestation. The fetus was found to have large hyperechoic lungs, flattened diaphragm and hydrops which form a triad in the detection of CHAOS. (Fig: 1) The patient and her husband were counseled regarding the risks involved on progression of the fetus till birth. The parents agreed to terminate the pregnancy voluntarily. A dead male fetus was delivered and sent for autopsy subsequently. An interesting finding noted during dissection of neck and thoracic organs was an abrupt ending of the trachea approximately 11 mm caudal to the lower end of larynx. (Fig: 2 & Fig: 3). The subsequent histopathology showing swollen cells confirmed the diagnosis (Fig: 4)