CSF samples from patients who have suffered a subarachnoid hemorrhage (SAH) may have a pink- to-yellow-tinged supernatant when the sample is centrifuged within one hour following collection.
The term used to describe the colored supernatant is xanthochromia. The color varies according to the substance causing the color and the length of time after the incident that the sample is examined. Xanthochromia is the result of breakdown products of RBCs that are present in the CSF due to the sah. The breakdown of RBCs and resultant xanthochromia begins two to three hours after the SAH and may persist for weeks.
A high serum bilirubin could also cause the CSF to be xanthochromic as could the plasma from a grossly bloody traumatic tap. However, RBCs introduced into the CSF because of a traumatic tap have not been in the fluid long enough to begin this breakdown process if the CSF is examined within one hour of collection.