HAEMATOLOGY Smear microscopy revision Smear microscopy revision: propositions by the GFHC

Abstract Despite the development of automated haematology analysers for reliable blood counts, examining blood smears under the microscope is still indispensable for confirming results when the data the analyser obtains are qualitatively or quantitatively abnormal. Although most criteria that lead to blood smear examination are widely recognised and used in laboratories, a multicentre survey indicates that they are still highly heterogeneous. To contribute to the harmonisation and standardisation of essential cellular haematology practice within the context of laboratory accreditation, the GFHC reviewed in detail the criteria used within the CBC to generate blood smears and has decided on a number of minimum recommendations. The conclusions presented in this article are based on a 'strong professional consensus', defining threshold values and various situations in which the blood smear review is desirable. They are presented as minimum recommendations for technical verification and biological validation. All laboratories are free to use more restrictive thresholds based on their patient populations