Investigations

• needle biopsy ^c
• spiral CT, lung scan (or pulmonary angiography if neither available) ^d
• bronchoscopy ^c

Why?

• Up to 27% of diagnoses are made using these investigations ^c

Needle biopsy and bronchoscopy can help diagnose malignancy or TB but not safely exclude them

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
pleural effusion c (pre-test probability: 48%)	malignancy or TB (culture or histology)	needle biopsy	69 (9.8 to 490)	98%	0.33 (0.24 to 0.44)	23%
pleural effusion c (pre-test probability: 68%)	malignancy (histology)	bronchoscopy	infinity (8.5 to infinity)	100%	0.45 (0.36 to 0.56)	49