Silent pericardial effusion in late pregnancy: a new entity.

Of 123 healthy pregnant women examined systematically by M-mode and two-dimensional echocardiography at various stages of gestation, 46 were in their late pregnancy (32nd-38th week) of whom 19 (41.3%) showed unexpected signs of pericardial effusion on the echocardiogram. Following Horowitz's criteria, the effusion was large in 2, moderate in 4, and small in 13 cases; in all women the condition was clinically silent. Clinical examination was normal in all but 3 women, in whom high blood pressure returned to normal after delivery. The ECG was usually normal (16 of 19 cases) or showed nonspecific ST-T changes. The entity appeared in late pregnancy (not before the 32nd week), was transient, and no longer could be seen within a month after delivery of a normal child. Cause of the effusion was attributed to excessive water and salt retention in those women with an abnormal echocardiogram who at this late stage of gestation had a mean weight gain significantly higher (P less than 0.03) than in others (13.60 +/- 4.28 vs 10.96 +/- 3.7 kg) - an observation not reported before in normal pregnancy. Since pericardial effusion cannot be detected by clinical examination or ECG, echocardiography affords a safe and reliable diagnostic approach.