The White Blood Cell Differential: Three Methods Compared

Abstract

The analysis of the automated blood cell count is an essential tool in haematological diagnostics. However, in the case of the white blood cell differential 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 samples from adults and 69 from children) including patients with oncological diseases. The comparison of the white blood cell differential revealed strong correlations between the results obtained with the ABX Pentra 120 Retic and the microscopy method, the Coulter STKS and the microscopy method and both automated methods (values of paediatric samples in parentheses; neutrophils: r_S≥0.933 (r_S≥0.951), lymphocytes: r_S≥0.907 (r_S≥0.945), monocytes: r_S≥0.584 (r_S≥0.459) and eosinophils: r_S≥0.963 (r_S≥0.966)). The analytical performance of automatic analysers for the detection of the morphological “left shift” was determined for all samples in comparison to the microscopical white blood cell differential. The sensitivity, specificity and efficiency depended strongly on the chosen threshold levels and were different for both analysers. The sensitivity for flagging a left shift increased with an increasing proportion of neutrophil bands, metamyelocytes, myelocytes and promyelocytes. Our study suggests that the ABX Pentra 120 Retic haematology analyser, as well as the Coulter STKS haematology system are useful tools for routine analysis in haematology.