Question 3.2

A 64-year-old male has been an in-patient in your Intensive Care Unit for one week following a subarachnoid haemorrhage.

The following data were obtained from a CSF sample taken from the external ventricular drain:


Patient Value

Normal Adult Range


3.8 mmol/L

2.2 – 3.9


0.46 G/L

0.15 – 0.5

White Cell Count

20x106 /L*

< 5

Red Cell Count

10 000x106 /L*

< 5

Interpret these results.

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College Answer

The WCC is elevated but the WCC:RCC ratio is normal (1:500) and represents normal findings after sub-arachnoid haemorrhage but does not exclude infection.


This is a faily straightforward data interpretation question. 10,000 / 20 = 500; which is the perfect ratio. This CSF is not infected, it just has blood in it.

Of course, in order to make a more accurate analysis, it would be good to also know the serum WCC, so that one may calculate the proper ratio.

A more detailed discussion of CSF analysis is available elsewhere.