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Original scientific paper

Effect of sample processing and time delay on cell count and chemistry tests in cerebrospinal fluid collected from drainage systems

Ana Mlinarić orcid id ; Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, Croatia
Željka Vogrinc ; Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, Croatia
Zrinka Drenšek ; Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia

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page 430-438

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Introduction: Cerebrospinal fluid (CSF) from extra-ventricular drainage (EVD) systems is routinely analysed to diagnose EVD–related bacterial
meningitis. We investigated the effect of time delay and sample processing on cell count and basic biochemistry results in EVD CSF to define optimal
turnaround time and whether manual and automated cell counting are comparable in such samples.
Materials and methods: In total, 32 EVD CSF samples were analysed. Baseline testing included cell counting (Fuchs-Rosenthal chamber and
Sysmex XE5000) and biochemistry analyses (glucose, lactate, proteins). Manual cell counting was also performed at intervals of 61-90 and 91-150
minutes from baseline in the residual sample. Biochemistry analyses were performed in samples before and after centrifugation at baseline and at
91-150 minutes interval.
Results: At 91-150 minutes total cell count (P < 0.001), large lymphocytes (P = 0.007), neutrophils (P < 0.001) and phagocytes (P = 0.006) obtained
by manual counting decreased and the number of disintegrated cells count increased (P = 0.016) compared to the baseline values. Considering
method comparison, proportional difference between methods for all cell (sub)groups was obtained, whereas polymorphonuclears also showed the
constant difference (y = 11.21 + 1.22x). Compared to centrifuged CSF, lower concentration of glucose and lactates were obtained in uncentrifuged
samples (P < 0.001) at baseline.
Conclusions: Manual cell counting should be performed within 60 minutes as any delay can alter results. The same counting technique should be
used to obtain longitudinally assessable results. Biochemistry tests are stable in uncentrifuged CSF up to 2.5 hours.


cerebrospinal fluid, extra-ventricular drainage system, cell count, biochemistry analyses, turnaround time

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