Bottom line: Dullness to percussion and asymmetric chest expansion are most accurate physical exam findings for diagnosing pleural effusion.
From a systematic review of studies evaluating diagnostic accuracy of the physical exam in pleural effusion. Table 71-4 summarizes sensitivities/specificities and positive/negative likelihood ratios for physical exam findings. Only one study evaluated all the common physical exam findings. Dullness to percussion and asymmetric chest expansion had the greatest positive LR (>8 in each case.) Each of these findings also had negative LR < 0.30.