Automated blood count analysis by trimodal size distribution of leukocytes with the SYSMEX E-5000

The automated haematology analyser, SYSMEX E-5000, measures and computes quantitative haematological parameters, and determines the size distribution of blood cells and platelets. After partial lysis, the analyser classifies the leukocytes into 3 populations: small cells (lymphocytes), intermediate sized cells (basophils, eosinophils, monocytes) and large cells (neutrophils, including band cells). One thousand blood samples from inpatients and outpatients were analysed automatically in the SYSMEX as well as being submitted to microscopic blood smear differentiation, and the results were compared. The trimodal size distribution of the automated analysis revealed 1.8% false normal results. Ten cases of eosinophilia of between 6.6 and 12.5% remained undetected by the automated method, which also failed to detect 7 cases of left shift with normal leukocyte count, as well as a single sample containing 2% of myelocytes. Both diagnostic sensitivity and diagnostic specificity were high, i.e. 97.1% and 81.8%, respectively. The predictive values were also high for both pathological and normal results. Since certain changes in blood cell morphology are not detected by the SYSMEX, certain clinical indications still call for a microscopic blood smear examination. With due regard to these limitations, the apparatus yields reliable results and economizes considerably the routine laboratory work load. In the present study, 31% of the microscopic blood cell differential counts were saved by using the SYSMEX E-5000.