Spectrophotometry is much more sensitive than the naked eye in detecting xanthochromia. Xanthochromia typically will not appear until 2-4 hours after the ictus. In nearly 100% of patients with an SAH, xanthochromia is present 12 hours after the bleed and remains for approximately 2 weeks. Xanthochromia is present 3 weeks after the bleed in 70% of patients, and it is still detectable at 4 weeks in 40% of patients.
A CT scan should have been performed (only proceed with CSF spectrophotometry in the case of negative/equivocal CT scans)
Other information : The CSF absorbance at 476 nm and the CSF protein will be reported.
Oxyhaemoglobin is a cause of interference, if the concentration is too high then there is a danger that this could mask any bilirubin present in the CSF specimen.
|CSF absorbance at 476 nm is < or = 0.007||Not consistent with SAH|
|CSF absorbance at 476 nm is >0.007 and CSF protein is normal||Consistent with SAH or other source of CSF blood|
|CSF absorbance at 476 nm is >0.007 and CSF protein is elevated||Consistent with SAH, other source of CSF blood, or increased bilirubin accompanying increased CSF protein – interpret results with caution.|
Cruickshank A et al. Revised National Guidelines for the analysis of cerebrospinal fluid in suspected subarachnoid haemorrhage. Annals of Clinical Biochemistry 2008; 45: 238-244.
Cannot be added on to an existing requestSpecimen Labelling Procedure