Comparison Between Manual and Automated Methods of Counting Reticulocytes and the Effect of Sample Storage on Reticulocyte Count: A Cross-Sectional Study from Southern India.

Reticulocyte count is a basic test in hematology. This study was done to compare manual and automated methods and to study the effect of sample storage on reticulocyte count. Analyses of samples (n = 86) were done at 2, 6, 24 and 48 h after blood collection. Manual counting was done from both freshly prepared slide and stored slide by microscopy on new methylene blue stained smears. Automated enumeration was on Sysmex XT-2000i analyser (Ret search II). The values of immature reticulocyte fraction (IRF) and low fluorescence reticulocytes (LFR) were also recorded. Comparison between two methods was done by Spearman's correlation and Mann-Whitney test. Effect of storage was analysed by repeated measures ANOVA. There was strong positive correlation between both manual and automated methods at 2, 6, 24 and 48 h. The differences between the manual and automated methods were not significant at 2, 6 and 24 h (p 0.975, 0.967 and 0.227). The difference between the freshly prepared slide and stored slide were significant at 6, 24 and 48 h (p 0.015, 0.004 and 0.001). The change in reticulocyte count with time, decrease in IRF and increase in LFR were not significant up to 6 h but were significant at 24 and 48 h after blood collection. Both the methods were accurate and correlated well with each other. Freshly prepared smears for manual counting were better than counting on stored slide. Up to 6 h after blood collection results obtained by both methods are acceptable. © Indian Society of Hematology and Blood Transfusion 2021.