<unk>  refers to blood in the pericardial sac of the heart. It is a cause of pericardial effusion, and can also cause cardiac tamponade.
The condition can be caused by trauma, but it has also been observed in patients on anticoagulant therapy.
Hemopericardium
Pneumopericardium
Chylopericardium
Urinothorax
Chylothorax
Hemothorax
Pneumomediastinum
Pulmonary hematoma