Evaluation of automated versus manual immature granulocyte counts

Abstract

Objective: Immature granulocyte (IG) count is the latest addition to the automated leukocyte differential generated by the Sysmex analyzers. The objective of this study was to assess the reliability of the automated IG counts. Methods: Automated IG percentages were compared with the corresponding manual IG percentages of 418 blood specimens. The data were divided into five groups. The difference between individual automated IG percentages and corresponding manual IG percentages was plotted and the number of outliers, based on Rumke's published 95% confidence limits, was determined for each group. Results: Of 418 automated IG percentages, 392 were within 95% confidence limits, with 26 outliers. More than half of the outliers carried also the "blast" flag, prompting a smear review. A significant difference between manual and automated IG percentage was noted when the manual IG count was greater than 10%. Conclusion: Automated and manual IG percentages compared fairly well with each other. We concluded that automated IG counts less than or equal to 10% may be considered reportable without a smear review.