Flagging performance of the Sysmex XN2000 haematology analyser

With the introduction of the Sysmex XN haematology analyser, the white blood cell differentiation channel (WDF) and abnormal cell detection channel (WPC) have been added with algorithms for flagging blasts and abnormal or atypical lymphocytes.

In this study, 2011 samples were evaluated on a Sysmex XN2000 analyser and microscopically reviewed using a CellaVision DM96 digital microscope.

A reference group of apparently healthy blood donors (n = 262) demonstrated in only three samples a positive suspect flag, which could not be confirmed microscopically. Positive WBC suspect flags were demonstrated in 3% of the 2011 samples. From the 55 samples with positive WBC suspect flags, an automatic reflex test was performed within the WPC. The WPC reflex test resulted in 10× Blast?, 15× Abnormal lymph? and 15× Atypical lymph? flags, which could be confirmed microscopically in 33% of these cases. A negative flagging was demonstrated in 15 cases. Microscopic evaluation demonstrated no abnormalities in these 15 cases. However, laboratory technicians also reported the presence of abnormal lymphocytes in 158 samples without an Abnormal lymph? flag.

In conclusion, the combined use of WDF and WPC resulted in a reduction of approximately 25% of the number blood smears. As a result of the various techniques for light microscopy and haemocytometry, the adequacy of the XN flagging for abnormal and atypical lymphocytes cannot be established with certainty. To improve the quality of the reported results, it is recommended that laboratory technicians incorporate the haemocytometry results and the flagging information in the microscopic slide review.