A thoracentesis on a child yields opaque fluid. This finding is NOT typically associated with which condition?

• A. Bleeding/trauma
• B. Malignancy/tumors
• C. Congestive heart failure
• D. Infection

Answer: (C)

Pleural fluid appearance mirrors the underlying process. Transudates, from fluid overload or low oncotic pressure, are usually clear or pale; exudates or hemorrhagic fluids tend to be opaque or turbid due to higher protein, inflammatory cells, bacteria, or blood.

Congestive heart failure in a child commonly causes a transudative effusion, so the fluid is typically clear rather than opaque. Opaque fluid points toward processes with abundant inflammatory cells or blood, such as infection (purulent effusion or empyema), malignancy with malignant cells, or trauma/bleeding. Therefore, opaque pleural fluid is not typically associated with congestive heart failure.