The chest x-ray shows cardiomegaly & Oreo Cookie sign.

The chest x-ray of this paediatric patient shows a massive cardiomegaly. On the lateral view, there is Oreo Cookie sign suggestive of pericardial fluid. The patient had a bedside ECHO which showed features of tamponade along with clinical features of hypotension. The patient was referred to specialist for emergency pericardiocentesis.

Oreo Cookie Sign may be seen on the lateral chest x-ray of a patient with pericardial effusion. A vertical opaque stripe (pericardial fluid) sandwiched between a vertical lucent stripe anteriorly (epicardial fat) & lucent stripe posteriorly (pericardial fat) resembles an Oreo cookie.

Further reading https://www.researchgate.net/figure/Oreo-Cookie-Sign-Lateral-chest-radiograph-shows-a-radiopaque-stripe-separating-two-radio_fig40_314914201