Pleural effusion fluid with increased hydrostatic pressure and decreased albumin is classified as what type?

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

Answer: (C)

The key idea is how the forces across capillary walls shape pleural fluid content—transudates come from systemic, noninflammatory factors that alter filtration, while exudates come from inflammation or injury that increases capillary permeability. When hydrostatic pressure inside capillaries rises and the blood’s oncotic (albumin) pressure falls, more fluid is pushed out into the pleural space and less protein is drawn back in. This creates a pleural effusion with low protein and low inflammatory content—a transudate. Examples include congestive heart failure (high hydrostatic pressure) and conditions with hypoalbuminemia (low oncotic pressure). In contrast, exudates arise from inflammation or infection that makes capillaries leak protein-rich fluid, often with higher protein and LDH; purulent or hemorrhagic effusions reflect infection or bleeding, not the described systemic pressure/oncotic changes.