Hemothorax

-The CT shows an effusion with relatively high attenuation; hemorrhage has an attenuation exceeding 35 Hounsfield units (HU) when the blood is fresh, and reaching 70 HU with clotted blood.
-There is contrast in the hemothorax representing ongoing bleed into the thorax.
-A rib fracture is visualized.

A hemothorax is blood in the pleural space. Trauma is the most common cause for a hemothorax. Less common causes include pulmonary embolism, metastatic disease, anticoagulant therapy, leaking aortic aneurysm.


http://eradiology.bidmc.harvard.edu/Classics/item.aspx?section=Emergency+Radiology&labelpk=33f0adab-853f-4010-a0e2-0756b3f1eac5&pk=7e7cde70-699d-4d26-8f9b-30752a17e137