CSF for Xanthochromia Testing
Collection of Specimens – (Five specimens required in total)
Label 4 white-topped universal containers and one grey-topped fluoride/EDTA tube with the patient’s name, NHS number (or hospital number), ward, date of birth, time that CSF was obtained AND the sequence order of sampling.
Collect the first specimen (0.5 mL) into the grey-topped fluoride tube for glucose and protein estimations and send to Clinical Biochemistry. Obvious blood stained samples will not be analysed.
Collect the next universal containers numbered 1- 3 (aim for a total of 2 mL) and send with the blue form to Microbiology, informing them by telephone that the samples will be arriving.
Collect the 4th universal container containing a minimum of 1 ml CSF (approx 20 drops from a Luer connector on a needle).
Protect this sample from the light, and send with the CSF fluoride sample and a gold-top blood sample together with the green form to Clinical Biochemistry.
Blue form – Microbiology samples (Universals 1, 2, and 3).
Green form – Biochemistry samples (Universal 4 and fluoride, plus a blood specimen (gold top).
- Clinical indication for request (including if the differential diagnosis includes meningitis).
- Time of lumbar puncture.
- Time of onset of symptoms/event.
- Result of CT scan.
Principle of the Test
This test is performed to attempt to identify those patients who have had a subarachnoid haemorrhage (SAH) but in whom the CT scan is negative. The spectrophotometric scan (printout illustrated above) detects bilirubin in CSF and this finding is consistent with a bleed into the CSF.
The formation of bilirubin after haemorrhage is a time-dependant process and bilirubin may not be detectable soon after the event (e.g. onset of severe headache). On current evidence it is recommended that CSF is not sampled until at least 12h after a suspected event.