Reticulocyte counts are widely used in laboratories to evaluate bone marrow erythropoietic activity and have great diagnostic and prognostic importance in the treatment of anemias. Reticulocytes are supravitally stained with new methylene blue or brilliant cresyl blue, which highlight the characteristic aspect of the reticulum visible by light microscopy. Known criteria were observed for good manual reticulocyte counting with special attention being paid to the preparation of reticulocyte slides, to counting fields without overlapping cells, and to the number of evaluated cells. The aim of this study was to evaluate the inter-observer variation and also to analyze the statistical error of manual reticulocyte counting. The Intraclass correlation coefficient (ICC) according to Bartko was used to evaluate the level of agreement among 12 laboratory technicians who evaluated the same 25 blood smears. The results of statistical analyses showed that the amount of random error, defined as (1-r2), varied from 4% to 60% among the technicians. Although imprecision occurred, the overall profiles were quite similar, and intraclass correlation coefficients indicated that the results obtained have clinical significance.
Haematology; statistical methods; manual reticulocytes count
