Which auscultation finding is most characteristic of a pneumothorax?

• A. Clear breath sounds
• B. Dull percussion on both sides
• C. Wheezes
• D. Hyperresonance on the affected side

Answer: (D)

Pneumothorax leaves air in the pleural space, which makes the affected area of the chest more air-filled and less dense. That extra air changes the sound heard when the chest is examined: percussion becomes hyperresonant on the side with the pneumothorax. This increased resonance accompanies reduced transmission of lung sounds, so breath sounds are diminished or absent over that side. The other options don’t fit this scenario: clear breath sounds would not be expected with a collapsed lung, dull percussion points to fluid or consolidation, and wheezes arise from airway narrowing rather than the presence of air in the pleural space. So, hyperresonance on the affected side best matches the classic exam finding for pneumothorax.