CHAOS BEFORE BIRTH: A RARE CASE OF FETAL AIRWAY OBSTRUCTION

Abstract

Congenital high airway obstruction syndrome (CHAOS) is a rare and potentially fatal condition characterized by complete or partial obstruction of the fetal upper airway, leading to a cascade of pathological changes including lung hyperexpansion, mediastinal compression, and fetal hydrops. We present a case of a 25-year-old G2P1L1 pregnant female who presented with bleeding per vaginum at 18 weeks of gestation for an antenatal anomaly scan. Ultrasound examination revealed a single live intrauterine fetus with bilateral echogenic and enlarged lungs compressing the heart, a flattened diaphragm, dilated trachea and bilateral bronchi, gross fetal ascites, hepatomegaly, echogenic collapsed bowel, and edematous abdominal skin. The nuchal fold thickness was borderline at 5.9 mm, and the abdominal circumference along with the estimated fetal weight were above the 97th percentile. These features were consistent with the diagnosis of congenital high airway obstruction syndrome, which was further supported by limited-sequence fetal magnetic resonance imaging. The patient had a history of completed treatment for pulmonary tuberculosis six months prior to conception. This case highlights the characteristic prenatal ultrasound findings of CHAOS and emphasizes the importance of early diagnosis for appropriate counseling and perinatal management planning, including consideration of ex utero intrapartum treatment procedures.