What physical examination finding is consistent with a pleural effusion?

A pleural effusion is characterized by an accumulation of fluid in the pleural space, which can affect various physical examination findings. When evaluating for a pleural effusion, one key finding is unilateral lag on chest expansion. This occurs because the fluid in the pleural space restricts the movement of the affected lung. During inspiration, the affected side will not expand as fully as the unaffected side, leading to a perceptible lag during the physical examination.

The other options represent findings associated with different pulmonary conditions. Hyperresonance to percussion suggests the presence of air in the pleural space, such as in pneumothorax, rather than fluid. Increased tactile fremitus typically indicates lung consolidation due to pneumonia, not fluid accumulation. Egophony is also associated with consolidation; it represents a change in the quality of voice sounds heard through the chest wall when lung tissue is airless and therefore denser, which is not the case in a pleural effusion where dullness is more likely to be noted.