TABLE 1

Prognostic assessment of pleural effusion: the American College of Chest Physicians guidelines

Pleural space anatomy		Pleural fluid bacteriology		Pleural fluid chemistry	Category	Risk of poor outcome	Drainage
Minimal, free-flowing effusion (< 10 mm on lateral decubitus image)	and	Culture and Gram stain results unknown	and	pH unknown	1	Very low	No
Small to moderate free- flowing effusion (> 10 mm and < 1/2 hemithorax)	and	Negative culture and Gram stain	and	pH ≥ 7.20	2	Low	No
Large, free-flowing effusion (≥ 1/2 hemothorax), loculated effusion, or effusion with thickened parietal pleura	or	Positive culture and Gram stain	or	pH < 7.20	3	Moderate	Yes
		Pus	4			High	Yes

Reprinted from Coulice et al,¹ with permission from Elsevier; www.sciencedirect.com/science/journal/chest.