Examination of blood cells is an essential part of the hematological investigation. The introduction of new physical principles for cell analysis incorporated into automated cell counters has provided new information about blood cells. Data related to both quantification and cell morphology features observed in peripheral blood examinations may be helpful during bone marrow analysis. In this brief review some of these new parameters are presented, such as the red blood cell distribution width (RDW) and indices related to volume, immaturity and hemoglobin content of reticulocytes. The interpretation of graphic displays (histograms of red cells, white cells and platelets) can provide further information that is not available from the assessment of numeric data. Other parameters and platelet indices, such as the mean platelet volume (MPV) and immature platelet fraction (IPF) are introduced, although they are still not standardized and must be used with caution. The quantification of various white blood cell populations present in peripheral blood and the advantages and limitations of automated counts are considered. Although the development of sophisticated automated blood cell analyzers has reduced the number of blood smear examinations, this type of procedure should be encouraged as the smear is an important tool in the diagnosis of several pathologic conditions.313178182(2008) Interpretação Clínica Do Hemograma, , Grotto HZW (ed), São Paulo: Editora AtheneuSandhaus, L.M., Meyer, P., How useful are CBC and reticulocyte reports to clinicians? (2002) Am J Clin Pathol, 118 (5), pp. 787-793Dixon, L.R., The complete blood count: Physiologic basis and clinical usage (1997) J Perinat Neonatal Nurs, 11 (3), pp. 1-18(2001) Practical Haematology, , Lewis SM, Bain BJ, Bates I (eds)., 9th ed. 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State of the art (2008) Am J Clin Pathol, 130 (1), pp. 104-116Sugimori, N., Kondo, Y., Shibayama, M., Omote, M., Takami, A., Sugimori, C., Aberrant increase in the immature platelet fraction in patients with myelodysplastic syndrome: A marker of karyotypic abnormalities associated with poor prognosis (2009) Eur J Haematol, 82 (1), pp. 54-6
