Blood cell morphology : controversies and alternatives

Abstract

In this thesis we describe controversial morphologic features in both microscopic and automated differentiation of blood cells. In addition, we have investigated alternative methods to overcome these shortcomings. Furthermore we describe the variance of microscopic counting of band cells and variant lymphocytes. We also describe the automated measurement of platelets in acute leukaemias. Finally, we describe alternatives for sepsis diagnosis. Microscopic differentiation of blood cells is a time consuming and inaccurate laboratory test, which requires expertise and experience. The inaccuracy is due to the small amount of cells, which is counted. Automated differentiation saves a lot of time and the obtained results are statistically more reliable. However, the flagging for abnormalities, shows less specificity and leads to overestimation of abnormalities. The technician usually does not have any clinical indication for a differential. This may result in unnecessary information for the clinician. Therefore most of the microscopic observations are superfluous and the differentials must be reduced. Additional laboratory parameters such as C-reactive protein (CRP) and procalcitonin (PCT) provide more information in addition to the absolute neutrophil count. Interleukins and cytokines may provide additional specific information. Neutrophil CD64 expression is a promising cellular sepsis marker. A high expression of neutrophil CD64 might be suggestive for a good prognosis in bacteraemia. Although controversies in microscopic examination of blood cells are profound, in some cases it is still required. In laboratories, a small group of experts should be formed and well trained by means of educational programmes and national quality assessments. When microscopic examination of white blood cells is necessary (indicated) a screening for abnormalities is sufficient. In that case microscopic white blood cell differentiation is not necessary at all.