Which clinical signs indicate pleural effusion on examination?

• A. Hyperresonant percussion and decreased breath sounds
• B. Normal breath sounds with dullness to percussion
• C. Dullness to percussion and decreased breath sounds over the affected area; possibly pleural rub
• D. Hyperresonant percussion with crackles

Answer: (C)

Pleural effusion causes fluid to collect in the space around the lung, dampening how sound travels and reducing air movement in the affected area. On exam this shows up as dullness to percussion because the fluid layer reflects less sound than aerated lung, and breath sounds over that area become decreased due to suppressed lung expansion beneath the fluid. A pleural friction rub may be heard if the inflamed pleural surfaces rub together, though it isn’t always present. This combination—dull percussion with decreased breath sounds, and sometimes a rub—is the typical exam finding for effusion. The other patterns point to different problems: hyperresonance suggests excess air (as in pneumothorax or emphysema), while normals or odd mixes of percussion and breath sounds don’t fit the fluid-filled space of an effusion.