The present study shows that other than in patients with cardiac trauma (i.
e., catheter-based cardiac intervention or cardiac surgery), the classifica
tion of pericardial effusions into hemorrhagic or nonhemorrhagic (serious)
groups had little diagnostic value with regard to etiology. Although serous
effusions are more frequently idiopathic than hemorrhagic effusions, each
group has a wide range of etiologies, and both groups are equally as likely
to be associated with a malignancy.