A sign often seen on a chest x-ray indicating pneumomediastinum is called what?

The spinnaker snail sign is a radiographic indicator that suggests the presence of pneumomediastinum, which is defined as the accumulation of air in the mediastinum. This sign can be observed on a chest x-ray as a specific pattern that resembles the shape of a spinnaker sail associated with a racing boat or a snail shell. The configuration arises from air dissecting along the connective tissue planes within the chest cavity, creating a characteristic appearance.

In contrast, the other terms mentioned in the options refer to different radiological findings that are not specific to pneumomediastinum. The butterfly pattern often relates to certain types of pulmonary edema, which presents differently on imaging. Air bronchograms can be indicative of conditions such as pneumonia, where the air-filled bronchi are seen against opacified alveoli—which is also a different pathological process. The double shadow sign reflects a distinct appearance sometimes noted in pleural effusions or other conditions, but does not correlate directly with pneumomediastinum. Understanding these distinctions helps nurses and healthcare professionals accurately interpret imaging findings in the neonatal population, especially when monitoring for complications such as pneumomediastinum.