Echocardiographic diagnosis of pulmonary thromboembolism in a preterm infant presenting with congenital chylothorax

A male newborn weighing 2,368 g was delivered via emergency cesarean section at 32 3/7 weeks of gestation following progressive fetal hydrops.He was diagnosed with congenital chylothorax and treated with bilateral chest drainage, diuretics, and fluid supplementation (including albumin and fresh frozen plasma).On day 19, SpO and mean blood pressure levels decreased to 60% and 25 mmHg, respectively.Chest X-ray showed a hyperlucent lung (Westermark's sign) and decreased left pulmonary vascularity (S Fig. 1A).Echocardiography revealed absent left pulmonary artery flow and mosaic flow in the right pulmonary artery (Video 1 and S Fig. 1B), reduced left pulmonary venous return, severe pulmonary hypertension, severe