Clinical features

Positive if the patient's headache worsens on flexing the patient's legs at the hip and extending them at the knees.

Why?

An absent Kernig's sign does not rule out meningitis

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
recent-onset headache and fever b (pre-test probability: 63%)	CSF pleocytosis ( 5 or more white cells per mm 3 of CSF )	positive Kernig's sign	- (0.62 to infinity)	100%	0.91 (0.82 to 1.0)	61%