Which term refers to fluid accumulation in the pleural space?

• A. Cystic Fibrosis
• B. Pneumonia
• C. Pleural Effusion
• D. Embolism

Answer: (C)

Fluid accumulation in the pleural space is called a pleural effusion. The pleural space lies between the lung surface and the chest wall and normally contains only a small amount of lubricating fluid. When more fluid collects there—due to conditions that raise hydrostatic pressure, lower oncotic pressure, increase vascular permeability, or hinder lymphatic drainage—it forms a pleural effusion. Clinically, this can lead to shortness of breath or chest discomfort, and imaging or physical exam findings (like dullness to percussion) help identify it. This term specifically describes the fluid-filled condition in the pleural space, distinguishing it from cystic fibrosis (a genetic lung disease), pneumonia (lung infection), or embolism (a blood vessel blockage).