Liver and lung have similar echogenicity early on and liver herniated into the chest may be mistaken for lung. Bowel within the chest is less likely to be missed; however, occasionally when the defect is present the intestinal contents do not herniate into the chest. Although the indications for extracorporeal membrane oxygenation vary from centre to centre, it is a therapy that has a recognised role in the management of some high-risk patients with congenital diaphragmatic hernia. Inhaled nitric oxide may have some benefit in diminishing pulmonary hypertension in infants with diaphragmatic hernia. The measurement of the lung is compared with some normal measure – often the fetal head. The lung-to-head ratio can be further normalised by comparing the lung-to-head ratio of the affected fetus with that of a normal fetus at similar gestational age. This is commonly performed in European centres to predict the most severely affected fetus.