Ultrasound diagnosis of an atypical pneumomediastinum.

The diagnosis of an atypical pneumomediastinum in a newborn was confirmed by ultrasound where an echogenic rim of air was noted around the heart. Ultrasound is suggested as an alternative to a decubitus film in differentiating between a pneumomediastinum (which usually resolves spontaneously) and a medial pneumothorax (which requires drainage).