Which physical examination finding supports a pleural effusion?

• A. Hyperresonant percussion at the base
• B. Clear breath sounds
• C. Increased chest movement
• D. Dull percussion at the base

Answer: (D)

Fluid in the pleural space dampens sound and compresses the underlying lung, so percussion over the affected base becomes dull. The fluid-filled pocket conducts percussion differently than air-filled lung tissue, producing a less resonant, “duller” note. This base dullness is a classic sign when a pleural effusion is present, especially as fluid tends to pool at the dependent base in an upright person.

In contrast, hyperresonant percussion suggests air in the chest, as seen with pneumothorax or certain chronic lung diseases; breath sounds are typically reduced or absent over the effusion, not clear; and the chest expansion is usually decreased on the affected side, not increased.