Cerebrospinal Fluid (CSF) Spectrophotometry (Xanthochromia)

Chemical Pathology

CSF spectrophotometry is performed to identify those patients who have had a subarachnoid haemorrhage (SAH) but in whom the CT scan is negative. The spectrophotometric scan detects bilirubin in the CSF and this finding is consistent with a bleed into the CSF.
Bilirubin is not detected in fresh blood from a traumatic tap (unless serum bilirubin was high).
This test is not indicated if the CT scan is positive

Lumbar puncture must be at least be 12 hours after onset of headache
CSF must be protected from the light after labelling and brought by hand to the laboratory (i.e. avoid use of air-shute)
A simultaneous blood sample for LFT's is also required for this investigation
If other CSF investigations are required please check CSF sample requirements link for further details.

A minimum of 1 mL CSF taken into a 30 mL Universal (tap #4 preferred) (approximately 25 drops from the Luer connector on the needle)

Also blood for liver function tests taken into a 5mL gold top tube (or rust top for the Acute Unit)

As bilirubin is degraded by light and concentrations are likely to be very low it is essential to protect these samples from the light. This can be achieved by wrapping the sample in aluminium foil or a hand towel before placing it in the plastic bag attached to the request card.
A blood sample for liver function tests, collected about the same time (±24 hrs) as the CSF, should accompany the request because serum total protein and total bilirubin results may be required for xanthochromia interpretation.
Samples from CGH are sent directly to GRH Pathology from the ward or from CGH Pathology if delivered there.

Label ALL bottles with

On the request card please indicate

Clinical reason for the investigation
The result of the CT scan. If there is CT evidence of a bleed this test is not indicated.
Date of any previous lumbar puncture (if within the last month)
The time and date of the onset of current symptoms/event
The date and time of the current lumbar puncture

CSF samples are analysed in GRH. Samples are analysed daily from 08:30 - 20:30. The test can be ordered as an urgent request.