Why human color vision cannot reliably detect cerebrospinal fluid xanthochromia.

BACKGROUND: Visual assessment of cerebrospinal fluid (CSF) for xanthochromia (yellow color) is practiced by the majority of laboratories worldwide as a means of diagnosing intracranical bleeds. METHODS: Colorimetric and spectrophotometric analysis of CSF samples for recognizing the presence of bilirubin either in low concentrations or in the presence of hemolysed blood. RESULTS: The experiments provide the physiological and colorimetric basis for abandoning visual assessment of CSF for xanthochromia. CONCLUSIONS: We strongly recommend relying on spectrophotometry as the analytical method of choice.