What does xanthochromia in cerebrospinal fluid indicate?

• A. Recent bacterial meningitis.
• B. Decreased protein content.
• C. Normal CSF findings.
• D. Yellow discoloration indicating previous subarachnoid hemorrhage or red blood cell breakdown.

Answer: (D)

Xanthochromia is yellowish coloring of the CSF caused by breakdown products of blood, specifically bilirubin formed as red blood cells in the CSF break down. This change indicates that there has been bleeding into the subarachnoid space, such as a subarachnoid hemorrhage, and that blood has remained in the CSF long enough for RBCs to lyse and bilirubin to accumulate. That timing aspect helps distinguish a hemorrhagic event from a purely traumatic tap, where blood is from the needle injury and may not show bilirubin unless enough time has passed.

So the yellow discoloration signaling prior blood in the CSF makes this finding the best indication of subarachnoid hemorrhage or red blood cell breakdown within the CSF. By contrast, bacterial meningitis typically presents with cloudy CSF and high white cells with high protein and low glucose, not a yellow discoloration from bilirubin. Decreased protein content or normal CSF findings would not explain xanthochromia.