The white blood cell differential: Three methods compared

The analysis of the automated blood cell count is an essential tool in haem atological diagnostics. However, in the case of the white blood cell differ ential the microscopy method, although tedious, often serves as reference. We evaluated the ABX Pentra 120 Retic haematology analyser in comparison to the Coulter STKS haematology system and the microscopy method with respect to accuracy, precision and reliability. We compared 308 samples (239 sampl es from adults and 69 from children) including patients with oncological di seases. The comparison of the white blood cell differential revealed strong correlations between the results obtained with the ABX Pentra 120 Retic an d the microscopy method, the Coulter STKS and the microscopy method and bot h automated methods (values of paediatric samples in parentheses; neutrophi ls: r(s)greater than or equal to0.933 (r(s)greater than or equal to0.951). lymphocytes: r(s)greater than or equal to0.907 (r(s)greater than or equal t o0.945), monocytes: r(s)greater than or equal to0.584 (r(s)greater than or equal to0.459) and eosinophils: r(s)greater than or equal to0.963 (r(s)grea ter than or equal to0.966)). The analytical performance of automatic analys ers for the detection of the morphological "left shift" was determined for all samples in comparison to the microscopical white blood cell differentia l. The sensitivity, specificity and efficiency depended strongly an the cho sen threshold levels and were different for both analysers. The sensitivity for flagging a left shift increased with an increasing proportion of neutr ophil bands, metamyelocytes, myelocytes and promyelocytes. Our study sugges ts that the ABX Pentra 120 Retic haematology analyser, as well as the Coult er STKS haematology system are useful tools for routine analysis in haemato logy.