Investigations

• cytology ^c

Cytology can help diagnose malignancy or TB, but not safely exclude it

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: 68%)	malignancy (other biopsies, clinical features, operation or autopsy)	cytology	infinity (22 to infinity)	100%	0.52 (0.46 to 0.58)	47%
pleural effusion c (pre-test probability: 39%)	malignancy or granulomatous disease (culture or biopsy)	> 95% lymphocytes in pleural fluid	2.0 (1.0 to 3.8)	56%	0.74 (0.54 to 1.0)	32%