Abstract
Background: Obtaining accurate, precise, and reliable platelet counts as a reference for the calibration of hematology analyzers has been a continuing problem due to varying results. We proposed the relativity of platelet count by Automated Cell Counter and Manual Haemocytometer with Peripheral smear for focusing the accuracy and & cost effectiveness, without compromising the accuracy of test results.

Methods: Seventy-Five blood samples in EDTA-anticoagulant vacutainer tubes were obtained and randomly divided into 3 group; Group I-normal control (n = 25), Group II-mild thrombocytopenia (n = 25) and Group III-severe thrombocytopenia (n = 25). Each blood sample had two peripheral blood smears made and stained on an automatic slide stainer. Peripheral blood smears were analyzed for platelet count by manual microscopy, an automated hematology analyzer Beckman Counter Diff 2 in all groups. The agreement between the two methodologies was assessed using the paired t-test and correlation coefficient analyses.

Results: The coefficient of variation values significantly differed in Group C and was high for automated cell counter. High positive correlation was also observed between Automated cell counter values and manual method (r=0.82, p<0.001) in group A and B. However, values in group C were not significantly correlated.

Conclusion: Based on the results observed in severe thrombocytopenia, the automated cell counter was more reliable and significant than the manual method. However, manual platelet count using by haemocytometry and morphological study of the blood smear may be promising if platelets are very low and giant platelets.

Key words: Thrombocytopenia peripheral blood smear, platelet count, automated Cell Counter and haemocytometer