Abstract

Background: Blood contamination is commonly observed in ventricular cerebrospinal fluid (CSF) samples from patients with extraventricular drainage systems. Because the introduction of blood may interfere with the white blood cell count as a useful marker for the diagnosis of an infection, correction for blood content would be desirable.

Methods: In a retrospective study, we analysed the use of correction formulas in 724 blood-contaminated ventricular CSF samples.

Results: Using a standard correction method the white blood cell count was not normalised in most CSF samples, with pleocytosis indicating an inflammatory stimulus set by the blood itself or by the foreign body. When correcting white blood cell counts in the CSF of culture-positive patients, some samples were normalised or overcorrected. In addition, correction of the CSF white blood cell count did not increase sensitivity and specificity for the detection of culture-positive CSF samples.

Conclusions: Correction is not necessary when using the white blood cell count as a parameter to predict CSF infection in ventricular CSF samples.

Clin Chem Lab Med 2008;46:842–8.