Pleural fluid volume | ≤ 50% of hemithorax | > 50% of hemithorax |
Pleural fluid configuration† | Free-flowing | Loculated |
Appearance on thoracentesis | Clear | Turbid or cloudy, or pus (empyema) |
pH level‡ | ≥ 7.20 | < 7.20 |
Lactate dehydrogenase level, U/L | ≤ 1000 | > 1000 |
Glucose level, mmol/L | ≥ 3.4 | < 3.4 |
Gram staining | Negative | Positive |
Aerobic and anaerobic bacterial culture | Negative | Positive |