On percussion, which finding indicates a healthy lung?

• A. Hyper-resonant
• B. Flat
• C. Dull
• D. Resonant

Answer: (D)

Percussion tone reflects air content and tissue density in the chest; a healthy lung yields a resonant sound because it is well air-filled. This sound is clear, hollow, and lasts longer than a dull or flat note. Hyper-resonant percussion suggests too much air, as seen with pneumothorax or emphysema; dullness points to fluid or solid consolidation, such as pneumonia or pleural effusion; flatness indicates very dense tissue, like bone or a thick chest wall. Therefore, the resonant finding best indicates a healthy lung.