National guidelines for analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage

The revised national guidelines for analysis of cerebrospinal fluid (CSF) for bilirubin in suspected subarachnoid haemorrhage ¹ omits reference to the rare occurrence of a false-positive computerized tomography (CT) brain scan that will likely lead to magnetic resonance angiography or CT angiography depending on local access to technology. Subarachnoid contrast enhancement mimicking subarachnoid haemorrhage has been described. ^2,3

The importance of the role of CSF spectrophotometry in clarifying this clinical scenario should be included in the national guidelines. The combination of the high Hounsfield attenuation characteristics on CT of contrast material versus blood in the CSF in addition to the negative spectrophotometric scan should aid diagnostic accuracy and spare the patient unnecessary intervention.

DECLARATIONS

Competing interests: None.

Funding: None.

Ethical approval: Not applicable.

Guarantor: WT.

Contributorship: WT, POS and PB are authors of this letter.

Acknowledgements: None.