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Diagnostic accuracy of Sysmex XN-1000 and Beckman Coulter DxH800 haematology analyzers in detection of platelet clumps in whole blood samples

Introduction: Pseudothrombocytopenia is a rare phenomenon resulting in falsely decreased platelet count on the haematology analyzer due to in vitroplatelet aggregation. It is one of the most common causes of incorrect platelet counts with estimated incidence in general population of 0.1 - 0.2%, and in hospital population up to 2%. Although mostly harmless, it can lead to additional laboratory testing, misdiagnosis, inappropriate platelet transfusions, and delayed diagnostic procedures. The aim was to examine diagnostic accuracy of haematology analyzers in detection of platelet clumps, by comparing obtained analyzer flags with microscopic examination of peripheral blood smear.Materials and methods: 199 whole blood samples were tested on Sysmex XN-1000 and 200 samples on two Beckman Coulter DxH800 analyzers (DxH800-1 and DxH800-2). The presence of platelet clumps was verified by light microscopy of peripheral blood smear stained with May-Grünwald Giemsa method. Results: Platelet clumps were confirmed in 50 out of 199 samples analyzed on Sysmex XN-1000, resulting in diagnostic sensitivity of 18% and specificity 85%. Out of 200 samples analyzed on DxH800-1 and DxH800-2, platelet clumps were confirmed in 29 and 26 samples, respectively. Obtained diagnostic sensitivity and specificity on DxH800-1 and DxH800-2 were 90% and 58%, and 85% and 53%, respectively.Conclusion: Each analyzer gave a certain number of false positive and false negative results. Since it is a screening method and every positive finding is fol-lowed by a confirmation method, it is important that the analyzer has high diagnostic sensitivity. As false-ly decreased platelet count may have significant clinical consequences, we believe that it is necessary to perform microscopic examination of peripheral blood smear in all samples in which platelet count < 10 0 x109/L was first obtained. These results indicate the need to conduct testing of the sensitivity of haematology analyzers for the presence of platelet clumps as part of the verification procedure.

Sysmex XN-1000, Beckman Coulter DxH800

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