Investigations

Why?

A chest X-ray or ultrasound scan can help diagnose an effusion

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
pleural disease and suspected pleural effusion c (pre-test probability: 69%)	pleural effusion (thoracentesis)	effusion on chest X-ray	4.2 (2.2 to 7.8)	73%	0.35 (0.21 to 0.60)	19%
		effusion on ultrasound scan	4.3 (1.5 to 12)	73%	0.73 (0.57 to 0.93)	32%