Overall equipment effectiveness, efficiency and slide review analysis of high-end hematology analyzers

The dilution evaluation as a corrective measure for interference in the white blood cell scattergram in Beckman Coulter DxH 900

BACKGROUND

The Beckman Coulter DxH 900 is a haematological analyser capable of counting and sizing blood cells, and obtaining a complete blood cell count (CBC). This analyses different parameters of red blood cells (RBC), platelets and white blood cells/leukocytes. Some automated CBC counters present limitations due to specimen characteristics, abnormal cells or both factors. In the presence of abnormalities, the DxH 900 has a flagging system, warning the laboratory technician that something needs to be verified. In the present work, we evaluated samples from oncologic patients, presenting a population erroneously perceived as being lymphocytes. The most common explanations for this situation are RBC resistant to lysis or serum hyperbilirubinaemia.

METHODS

In an attempt to solve and understand what the cause of this problem might be, we diluted our samples (1:3) and analysed the serum total bilirubin. To identify cells' abnormalities, the samples were also analysed by manual DLC counts. During the study, we also checked the different flags presented by the equipment.

RESULTS

The results evidenced that the major interference was due to RBC lysis resistance, corresponding to 94.7% of the cases, while hyperbilirubinaemia was only present in 73.4%. Besides, we determined that some samples with normal bilirubin levels also presented interference, suggesting that hyperbilirubinaemia was not the main cause of the error. The most recurrent flag observed was "High event rate".

CONCLUSION

The dilution solved all of the observed interferences. The results between diluted and manual counts showed a strong correlation, leading us to introduce dilution in our laboratory routine.

Evaluation of the WBC-differential flagging performances and accuracy of the HORIBA Yumizen H2500 cell counter in oncology patients from a single institution

INTRODUCTION

The Yumizen H2500 (YH2500) cell analyser was compared to the Pentra DX Nexus (both from HORIBA Medical) to evaluate the efficiency of the new YH2500 technology for the WBC-differential in samples from oncology patients with WBC-diff abnormalities.

MATERIAL AND METHODS

The 220 samples with slide review criteria on the Nexus were systematically analysed on the YH2500. The WBC-diff was compared to flow cytometry (FCM). The 100 additional samples with Monocyte/Neutrophil separation flags were evaluated. The flagging performance and the accuracy of the WBC-diff were analysed.

RESULTS

The YH2500 generated fewer flags than the Nexus (47.73% vs 66.64%; p < .0001), except for Monocyte/Neutrophil flag (15.5% vs. 2.7%; p < 0.0001). Overall performances were higher on the YH2500 (Sensitivity, 100 vs. 89.6%; Specificity 81.0% vs. 50.9%; PPV, 74.3% vs. 62.9%; NPV, 100% vs. 69.5%; Efficiency, 87.7% vs. 69.5%). YH2500 showed a statistically significant better correlation with FCM for the 6-part differential than the Nexus. On 134 samples with Monocyte/Neutrophil separation flag, it was shown that, in samples with less than 10% monocytes on the YH2500, the results of monocyte and neutrophil counts were comparable to the manual count, and that these samples did not need a slide review if no other main criterion for review was present.

CONCLUSION

The YH2500 demonstrated better performance characteristics than the previous cell counter, the Nexus. Its implementation in our laboratory routine work significantly improved the practice workflow, decreased the number of manual cell counts and increased the pertinence of slide review and reporting of the microscopic count.