Pathology Handbook

CSF - Spectrophotometry (investigation of ?SAH)


CSF xanthochromia

Clinical Indications

The test is performed to try and identify patients who have had a subarachnoid haemorrhage (SAH) but in whom the CT scan is negative.  After SAH, haemolysis of  erythrocytes releases haemoglobin, which is converted to bilirubin.  Bilirubin concentration reaches a maximum at about 48 hours and may last for 2 to 4 weeks after extensive bleeding. Because the formation of bilirubin after haemorrhage is a time-dependent process, CSF must be sampled at least 12 hours after a suspected event.

Request Form 

Request on ICE


On request.

Specific Criteria

The following must be indicated on the request form:
 - Clinical indication for request
 - Result of CT scan
 - Time of onset of symptoms/event
 - Time of lumbar puncture
 - If the differential diagnosis includes meningitis

Patient Preparation

CSF must be sampled at least 12 hours after a suspected event.

Turnaround Time

Within 24 hours


CSF collected sequentially (the first few ml. of fluid should not be used for this investigation). The first fraction should be collected into a grey top fluoride tube for glucose. CSF may also be required for microbiology and should be collected next (3 fractions into 3 white capped universals). The specimen for spectrophotometry must be the last fraction taken and ideally, at least the 4th.  A blood sample (yellow top SST) should be taken at the same time for bilirubin, total protein and glucose.


Minimum of 1 ml.


White Capped Universal and an SST blood sample


Sample should be protected from light and transported to Clinical Biochemistry immediately.

Lab Handling

Centrifuge CSF sample as soon as possible after receipt and within 1 hour of collection. Store supernatant in the dark at 4C until analysis.

Causes for Rejection

CSF sample taken less than 12 hours after suspected event.
Insufficient information regarding timing of sample; unlabelled or incorrectly labelled sample
Delay in sample reaching laboratory


See the laboratory report