Pleural effusion in congestive heart failure (CHF) if it is unilateral, is found more often on right side. This is supposed to be due to the larger pleural surface of the right lung predisposing to transduation of more fluid. In one analysis, unilateral right-sided effusions were twice as common as left-sided effusions in CHF (28% vs 15%). This data also shows that bilateral pleural effusion is more common than unilateral pleural effusion in CHF.
