Congenital hydropericardium associated with the herniation of part of the liver into the pericardial sac.

A congenital pericardial effusion without a clinically obvious cause is rare. The presentation, diagnostic studies, and anatomic findings in three such cases are described. It is postulated that the fluid within the pericardial sac, was a transudate produced by a partially strangulated portion of the liver, trapped in an intrapericardial hernia with sac, which was present in each case. Encroachment with compression by the enlarged pericardium on the developing lung bud structures is the reason given for the pulmonary hypoplasia, associated with this form of diaphragmatic hernia. Severe pulmonary insufficiency was the presenting feature, while cardiac tamponade is noted for its absence, in these cases.