Which physical examination finding is most characteristic of pleural effusion?

Which physical examination finding is most characteristic of pleural effusion?

• A. Decreased tactile fremitus
• B. Dullness to percussion
• C. Decreased breath sounds
• D. Pleural friction rub

Answer: (B)

Fluid in the pleural space changes how sound travels through the chest. On percussion, this area produces a dull, thud-like note rather than the hollow resonance of air-filled lung. That dullness is the hallmark sign because the fluid directly displaces air-containing lung tissue and dampens sound transmission. Other findings can accompany effusion—breath sounds may be reduced or absent as the lung is compressed and air entry is blocked, and tactile fremitus may be decreased for the same reason—but dullness to percussion is the most characteristic. A pleural friction rub suggests pleuritis with roughened pleural surfaces and is not typical of a simple effusion.

Fluid in the pleural space changes how sound travels through the chest. On percussion, this area produces a dull, thud-like note rather than the hollow resonance of air-filled lung. That dullness is the hallmark sign because the fluid directly displaces air-containing lung tissue and dampens sound transmission. Other findings can accompany effusion—breath sounds may be reduced or absent as the lung is compressed and air entry is blocked, and tactile fremitus may be decreased for the same reason—but dullness to percussion is the most characteristic. A pleural friction rub suggests pleuritis with roughened pleural surfaces and is not typical of a simple effusion.