Context: Automated methods of enumerating nucleated red blood cells (NRBCs) in blood are gaining acceptance in many laboratories.
Objective: To evaluate the performance of Sysmex XE-2100 in enumerating NRBCs in peripheral blood.
Design: Automated relative number of NRBCs per 100 white blood cells (NRBC%) results for a total of 460 specimens run on the XE-2100 were compared with manual NRBC% results obtained by performing a 100-cell differential on a Wright-stained smear prepared from each specimen. To assess within-day reproducibility, 64 specimens were rerun on the XE-2100, and a second 100-cell differential was performed on the original blood smear. Excel software was used for data analysis.
Results: Regression analysis of automated NRBC% versus manual NRBC% yielded a correlation coefficient of 0.9712. No NRBCs were seen in the blood smear on 35 (15.1%) of 232 specimens with automated NRBC% of 0.1 to 1.9. The XE-2100 generated an NRBC% of 0.0 on 5 (6.8%) of 74 specimens, revealing 1 NRBC per 100 or more white blood cells by blood smear examination. The mean percent difference between duplicate automated results was 16.7 compared with 78.1 for the duplicate manual results. There were 9 instances in which the XE-2100 either did not detect the presence of more than 8 NRBCs per 100 white blood cells or generated an automated NRBC% of 18.1 or 18.8 when the smear revealed none. All of these were, however, flagged for smear review.
Conclusions: Overall correlation between the automated and manual results was excellent. The automated method revealed better precision than the manual method. The number of specimens with false automated results was very small, and all were flagged for verification by a smear review.