Comparison of Platelet Counts Estimated by Peripheral Blood Smear Examination and Automated Haematology Analyzer

Abstract

Introduction: Platelet count estimation is one of the common as well as important investigations in clinical practice to diagnose many diseases like dengue, malaria, etc. Different methods for platelet estimations are available. These methods are manual counting semi-automated and automated hematology analyzer counting, platelet count estimation by peripheral blood smear (PBS) method, etc. Semi-automated or automated analyzers may produce erroneous results in the presence of particles or light scatter like giant platelets, fragmented red blood cells, and platelet clumps, so alternative methods like PBS examination can be used for validation. Aim: To compare platelet count estimation performed by the automated cell counter method and the PBS examination method. Objective: Peripheral Blood smear examination acts as a good quality control tool to validate the results produced by the automated cell counter. Materials and Methods: The present study was carried out in the Department of Pathology, Akshaya Health Centre, Urban Bangalore. The study included 100 random blood samples collected into ethylenediaminetetraacetic acid (EDTA) vacutainers over 3 months. These were analyzed by both peripheral blood smear and automated cell counter for platelet estimation. The statistical analysis was done for test performances and their comparisons by using the coefficient of variation (CV), linear regression, and mean differences with SPSS software. Results: No significant difference (p = 0.06635) was observed between the manual peripheral blood smear (PBS) method (platelets average per 100x, multiplied by 15000/ µl) of platelet estimation (207.13 ±15.898 x 1000/ µl) and that of automated cell counter platelet value (206.53 ±16.278 x 1000/ µl). A significant positive correlation was observed between the results of both methods (r=0.9995, p < 0.001) when analyzed by the Pearson correlation test. Conclusion: The peripheral blood smear platelet estimation results are comparable with automated analyzer results. Hence, the PBS examination serves as a quality control tool in assessing the results of the automated cell counters.