What physical assessment finding indicates a large pleural effusion?

• A. Hyperresonance and crackles at the base.
• B. Dullness on percussion and decreased breath sounds over the effusion.
• C. Clear lungs with no abnormal sounds.
• D. Increased fremitus.

Answer: (B)

A large pleural effusion dampens and muffles lung sounds because fluid accumulates in the space around the lung, separating it from the chest wall. This makes percussion dull rather than resonant, since fluid conducts sound differently than air. At the same time, the fluid and collapsed lung reduce the amount of air movement you can hear, so breath sounds become decreased or absent over the affected area.

That’s why this option is the best match: dullness on percussion paired with decreased breath sounds over the effusion. Other choices don’t fit the classic exam findings. Hyperresonance suggests extra air, as in pneumothorax or emphysema, not fluid. Clear lungs with no abnormal sounds wouldn’t indicate an effusion. Increased fremitus occurs with lung consolidation, not with a fluid-filled pleural space.