Accuracy and utility of differential white blood cell count in the neonatal intensive care unit.

The clinical utility of the complete blood cell count (including the differential white blood cell count) as a means to follow the course of infants in a neonatal intensive care unit was assessed. Utility was judged for three purposes: (1) predicting the onset of clinically unrecognized disease, (2) assessing the severity of current disease, and (3) following a trend during treatment. Neither conventional nor automated differential counts were useful for surveillance (predicting the onset of clinically unrecognized disease). The white blood cell count, the platelet count, and the absolute immature neutrophil count and immature/total neutrophil ratio were useful to assess the severity of current clinical events. The white blood cell count was superior to the differential count for following trends in patients' conditions. Information regarding nuclear immaturity derived from automated counts and the cost and slowness of the manual differential count are good indications for decreased use of conventional counts, increased use of certain features of the automated differential, or both, in neonatal intensive care units.