Investigations

Why?

A milky appearance makes a chylous effusion more likely.

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: 27%)	chylous fluid (chylomicrons in pleural fluid)	milky appearance	25 (6.0 to 100)	90%	0.54 (0.40 to 0.73)	16%

Note:

• Chylous fluid increases the chance of lymphoma (~ 50% of patients). Other common causes are post-operative/ traumatic (24%) or idiopathic 13%.^c