Here is an image of the right pleural effusion obtained from a dialysis patient who suffered a cardiac arrest and being evaluated by nephrology for continuous renal replacement therapy.

Below are two more images – one obtained from the side (anterior to mid-axillary) and the other subcostal view of the right pleural effusion. On the subcostal view, note the actual collapsed lung, with more typical appearance. Then what is the other structure that appears like a blossoming flower?

It is likely solidifying blood in the pleural space secondary to cardiopulmonary resuscitation. Some educators call this Seaweed sign or a clot-fish. Review of chest X-ray did not show obvious rib fractures but interestingly, the patient was administered tissue plasminogen activator (tPA) during the CPR as pulmonary embolism was suspected. Spontaneous hemothorax has been reported previously in the setting of tPA administration. While we previously discussed a case of hemothorax, the echotexture of clot in this patient (probably early) is different and noteworthy. The patient died soon after these images were acquired and therefore no further imaging studies are available.