The Accuracy of Platelet Counting in Thrombocytopenic Blood Samples Distributed by the UK National External Quality Assessment Scheme for General Haematology

Abstract

A knowledge of the limitations of automated platelet counting is essential for the effective care of thrombocytopenic patients and management of platelet stocks for transfusion. For this study, 29 external quality assessment specimen pools with platelet counts between 5 and 64 × 10(9)/L were distributed to more than 1,100 users of 23 different hematology analyzer models. The same specimen pools were analyzed by the international reference method (IRM) for platelet counting at 3 reference centers. The IRM values were on average lower than the all-methods median values returned by the automated analyzers. The majority (~67%) of the automated analyzer results overestimated the platelet count compared with the IRM, with significant differences in 16.5% of cases. Performance differed between analyzer models. The observed differences may depend in part on the nature of the survey material and analyzer technology, but the findings have implications for the interpretation of platelet counts at levels of clinical decision making.

A novel method to estimate platelet counts from peripheral smears: A study comparing a new method of platelet estimation with existing methods.

“…Accurate measurement of the platelet counts is essential particularly in the management and monitoring of patients with thrombocytopenia [1,2,6] . Automated hematology analyzers in spite of the various advances have the limitation of inability to produce precise and reproducible platelet counts particularly in patients with thrombocytopenia [1,2,6,7] .…”

“…Automated hematology analyzers in spite of the various advances have the limitation of inability to produce precise and reproducible platelet counts particularly in patients with thrombocytopenia [1,2,6,7] . Presence of background debris, microorganisms, fragmented RBCs, apoptotic bodies from white blood cells and markedly microcytic RBCs can all hinder an accurate measurement of platelets in automated hematology analyzers by mimicking the platelets due to their small size.…”

“…The traditional gold standard method for measuring platelet counts was the phase contrast microscopy [1] . But this method is time-consuming and lacks precision in cases with low platelet counts.…”

“…But the accuracy of this method in predicting the platelet count in patients with thrombocytopenia is questionable [1,2] . Hence there is a need for an alternate method to perform the platelet counts with reasonable degree of accuracy in patients with thrombocytopenia.…”

State of the Art in Platelet Function Testing

“…Optical counting methods like light scatter or fluorescence methods have been introduced for automated platelet counting. The RBC/Platelet Ratio International Reference Method (IRM) uses flow cytometry to count large numbers of cells rapidly, accurately, and precisely [82,83]. Platelet count is derived from the ratio of fluorescent platelets, labeled with a monoclonal antibody, to collected red blood cells.…”