Determination of Platelet and White Blood Cell Counts from Peripheral Blood Smear: An Indispensable Method in Under-resourced Laboratories

Objective: Blood smear examination serves as a quality control tool in verifying the results generated by the automated analyzer and identification of abnormal or immature cells amongst other functions. This study was undertaken to estimate platelet and White Blood Cell (WBC) counts from Peripheral Blood Smear (PBS) and to correlate them with the results from automated method.

Materials and Methods: Fifty blood samples collected into K3 EDTA from 30 males and 20 females whose ages were from 2 to 50 years, and attended General Out-Patient Department (GOPD) of Aminu Kano Teaching Hospital, Kano between May and November, 2015 were considered for the study. Each blood sample was used for the determination of full blood count using Swelab Alfa hematology analyzer, and preparation of stained blood films using standard laboratory methods.

Results: There were significantly lower values of platelet count (using multiplication factor of 15.0 x109/L) and white blood cell count (using multiplication factor of 2.0 x109/L) to derive (22.42±60.77) x109/L and (4.49±1.04) x109/L by manual (PBS) method as compared to (267.86±77.28) x 109/L and (5.86±1.36) x109/L respectively, for automated method (P<0.001). However, there was no significant difference in estimated platelet count by manual (PBS) method using multiplication factor of 20.0 x109/L compared to automated method (P>0.05). Fairly strong positive correlations were observed for platelet and white blood cell counts when manual method was compared to automated method (r= 0.6828 - 0.7321, P<0.05).

Conclusion: It can be concluded that multiplications factors of 20.0 x109/L per 100X, objective lens and 2.7 x109/L per 40X, objective lens can be used for average numbers of platelets and white blood cells respectively to estimate platelet and white blood cell counts from PBS as the results are comparable to that of the hematology analyzer.