Performance evaluation of the Sysmex XE-5000 hematology analyzer for white blood cell analysis in cerebrospinal fluid.

CONTEXT

The newest generation hematology analyzer, Sysmex XE-5000 (Sysmex Corporation, Kobe, Japan) is equipped with an improved body fluid analysis mode.

OBJECTIVE

To evaluate the applicability of the XE-5000 analyzer to white blood cell (WBC) analysis in cerebrospinal fluid (CSF).

DESIGN

A total of 425 routinely collected, consecutive CSF samples were included in the study. For a comparison of total WBC counts, the results of routine chamber counts were grouped into categories of 0 to 5 (n  =  330), >5 to 10 (n  =  36), >10 to 50 (n  =  39), >50 to 200 (n  =  15), and >200 (n  =  5) WBC/µL. Microscopic differential counts were performed using cytospins from 276 samples. Results were grouped according to the percent content of polymorphonuclear (PMN) cells, 0% to 25% (n  =  263), >25% to 50% (n  =  7), >50% to 75% (n  =  3), and >75% to 100% (n  =  3) of WBC. Corresponding results of XE-5000 analysis were matched to these particular count categories.

RESULTS

For total WBC counts, the proportions of samples correctly classified by the XE-5000 from the percentage groups described above were 88%, 47%, 72%, 93%, and 100%, respectively. After the two lowest count categories were combined into one range of 0 to 10 WBC/µL, matches increased to 95%. For PMN counts in the 0% to 25% group, 37% of samples were misclassified by the XE-5000. Conversely, for samples with microscopic PMN counts of more than 25%, there was a trend toward underestimation by the XE-5000. Mismatches were most pronounced in samples with fewer than 10 WBC/µL.

CONCLUSIONS

The Sysmex XE-5000 hematology analyzer yields valid total CSF cell counts and may be considered an acceptable alternative to the traditional chamber method, even for samples with low WBC counts. However, it cannot be recommended as a suitable alternative for manual differential cytologic workup.