Reliability of echocardiography in quantitating pericardial effusion: a prospective study.

A method of estimating the volume of pericardial effusion by echocardiography has used the difference between the cubed diameters at end-diastole of the pericardium and epicardium. To evaluate the reliability of this technique in quantitating the volume of pericardial effusion in a prospective study, 22 echocardiograms were obtained in six patients before and after 11 separate pericardiocenteses. The correlation coefficient between the actual volume of aspirated pericardial effusion and the echocardiographically estimated volume of aspirated pericardial effusion was r = 0.27 (P not significant). The volume of pericardial effusion aspirated was overestimated or underestimated by echocardiography by more than 100 ml in seven of 11 estimations (64 percent) and by more than 150 ml in five of 11 estimations (45 percent). Therefore, although echocardiography is the procedure of choice in diagnosing the presence of pericardial effusion, it is not an entirely accurate method of quantitating the volume of pericardial effusion. However, echocardiography can differentiate a large effusion from a moderate or small effusion.