Q: 32 year old female admitted to ICU with seizure, preceded by severe headache. There is a strong suspicion of subarachnoid hemorrhage (SAH). Noncontrast CT of head is reported negative. Neurosurgeon requests you to perform lumbar puncture (LP) to confirm SAH. As you collect all four test tubes of CSF, you suspect some 'pinkish' tinge in fluid. What is your suspicion? 

 Answer: Xanthochromia 

Xanthochromia which is actually a pinkish or a yellowish tint signifies, hemoglobin degradation products in CSF, and is highly suggestive of SAH. The best way to confirm xanthochromia is by comparing a vial of CSF with a vial of plain water held side by side against a white background in bright light. It is important to perform this visual inspection quickly after LP to distinguish it from traumatic LP. The presence of xanthochromia in just performed LP indicates that blood has been in the CSF for at least two hours.

Reference:

Wijdicks EF, Kallmes DF, Manno EM, et al. Subarachnoid hemorrhage: neurointensive care and aneurysm repair. Mayo Clin Proc 2005; 80:550.