In pleural effusion, which type is typically seen with heart failure?

• A. Exudative
• B. Transudative
• C. Purulent
• D. Hemorrhagic

Answer: (B)

In pleural effusion, the distinguishing feature is whether the fluid is a transudate or an exudate, based on how it forms. Heart failure causes a transudative effusion because the primary issue is elevated hydrostatic pressure pushing fluid out of the capillaries into the pleural space. This type of fluid leakage isn’t driven by inflammation or increased vascular permeability, so it contains relatively little protein or inflammatory cells. Light’s criteria help differentiate: transudates have lower protein and LDH in the pleural fluid relative to blood. Exudates, by contrast, come from inflammation, infection, malignancy, or trauma and show higher protein and LDH, reflecting increased vascular permeability and inflammatory activity. Purulent effusions indicate infection with pus, while hemorrhagic effusions suggest bleeding. So, in heart failure, the pleural fluid is typically transudative.