Platelet Estimation by Manual and Automated Methods
Keywords:
manual platelet count, Platelet/RBC ratio, Peripheral smear, diagnostic accuracy
Abstract
Background: Accurate platelet estimation is essential for the management of the patients with thrombocytopenia. Automated analyzer by its quick and reliable platelet estimation has overtaken the manual methods. But sometimes do produce erroneous results which are to be cross checked by manual methods. Hence this study was undertaken to compare the traditional manual method and alternate method based on Platelet/RBC ratio for estimating platelets in peripheral smear and to find the most accurate method for detecting Thrombocytopenia. Methods: 100 samples of EDTA anticoagulated blood is analysed by automated analyzer, then thin peripheral smear is prepared. Manual counts are performed by 1: Traditional Method- average platelet count / 10 Oil immersion field (OIF) x 15,000, 2: Alternate method -platelet/1000 red blood cells (RBC) multiplied by RBC count. Manual methods were compared with the automated analyzer using students t test. The Sensitivity, Specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and Likelihood ratio (LR) for positive tests were also calculated for the manual and alternate methods in detecting thrombocytopenia. Result: The students t test shows no difference in the platelet counts estimated by traditional method and alternate method. Further the results of sensitivity, specificity, PPV, NPV and LR for positive tests show the traditional and Alternate method can give fairly accurate results. Conclusion: The manual method of platelet estimation is found to be the most accurate and can used to quality check the automated analyzer or can be used in underprivileged laboratories, for aiding in proper management of the patient.References
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2. Bajpai, et al. Platelet count by peripheral blood smear: Reliable, rapid, cost-effective method to assess degree of thrombocytopenia. International Journal of Medical Science Research and Practice.2015; Vol 2 ( 2): 90-93.
3. Umarani MK, Shashidhar B. Estimation of platelet count from peripheral blood smear based on platelet: red blood cell ratio. A prospective study in a tertiary care hospital. Indian Journal of Pathology and Oncology, April-June 2016;3(2);351-353
4. Ninama NJ, Nirali K Shah. Impedance platelet count in severe microcytosis-study of 161 patients. NHL Journal of Medical Sciences. Jan 2014;Vol 3( 1):32-36.
5. Webb DI, Parker L, Webb K. Platelet count assessment from peripheral blood smears (PBS).Alaska Med. 2004 Oct-Dec;46(4):92-5.
6. Brahimi et al. Platelet count from a blood smear. Turk J Hematol 2009; 26: 21-4.
7. Malok M et al. Comparison of two platelet count estimation methodologies for peripheral blood smears. Clin Lab Sci. 2007 Summer;20(3):154-60.
8. Sherrie L P. Examination of the Blood and Bone Marrow. In: John P. Greer, John Foerster, George M. Rodgers, Frixos Paraskevas, Bertil Glader, Daniel A. Arber, Robert T. Means Jr, editors. Wintrobe’s Clinical Hematology.12th ed. Philadelphia: Lippincott Williams & Wilkins; 2009.pp. 9-46.
9. Cheryl B, M.S. Peripheral blood smear. In: Shirlyn B. McKenzie, Mark Cohen, Melissa Kerian editor. Clinical Laboratory Hematology. New Jersey: Pearson Education.
10. Sudalaimuthu M et al. A novel method to estimate platelet counts from peripheral smears: A study comparing a new method of platelet estimation with existing methods. Annals of Pathology and Laboratory Medicine, Jan - Feb 2017; Vol. 04( 01); 77-82.
11. Dr. Ajamal S B et al. Study of platelet count on the basis of Red cell: Platelet ratio. JMSCR. Oct 2015; Volume 03 (10); 7742-45.
12. Bakhubaira S. Automated Versus Manual Platelet Count in Aden. Clinical & Experimental Pathology.2013. vol 3 (3)
13. Babadoko AA, Ibrahim IN, Musa AU, Usman N. Reproducibility of hematological parameters: Manual versus automated method. Sub-Saharan Afr J Med. 2016; 3:65-70.
14. Imoru M. Determination of platelet and white blood cell counts from peripheral blood smear: an indispensable method in under-resourced laboratories. International Blood Research and Reviews.2016; 5(2): 1-7.
15. Anitha K et al. Comparison of Platelet Count by Peripheral Smear Method and Automated Method in pregnant women. National Journal of Physiology, Pharmacy & Pharmacology,2014; Vol 4 ( 1 ); 39 – 42.
Published
2019-11-29
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