What is 100% sensitive for distinguishing SAH on LP from traumatic LP (skin vessels)?,”Xanthochromia (Presence of bilirubin in LP, takes 12 hours to breakdown RBC into bilirubin).CT sensitivity decreases with time (best when <12h). Xanthochromia remains highly sensitive for 2 weeks.Best done to diagnose SAH 12 hours - 14 days after onset of symptoms whereas CT is better < 12 hours after onset."