The correlation between automated hematology and manually read smears for the determination of nucleated red blood cells in umbilical cord blood

Objective. To determine the correlation between automated hematology nucleated red blood cell counts and manual counts in umbilical cord blood. Methods. Umbilical cord venous blood was obtained after cord clamping at the time of delivery. The number of nucleated red blood cells per one hundred white blood cells was measured using an automated hematology analyzer and compared with direct microscopic visualization of prepared slides by experienced hematology technicians. Results. The umbilical cord blood from 128 women was studied. The mean, median and standard deviations of nucleated red blood cell counts were not significantly different between the automated reading and the manual reading ( mean 9.3 +/- 11.2 versus 9.1 +/- 13.1, respectively, P = 0.76; median 5.9 versus 5.0, P = 0.95; range 0 - 77, 0 - 105). Automated derived nucleated red blood cell counts and manual numbers were highly correlated with a correlation coefficient of 0.794. Conclusion. The automated hematology analyzer readings of nucleated red blood cell counts correlate well with readings by laboratory hematologists.