Refining the white blood cell differential: the first flow cytometry routine application.

A Complete Blood Count performed by an automated hematology analyzer frequently needs a microscopic slide review. This step is time consuming and requires experienced personnel. Recently, several teams have proposed and validated convenient combinations of monoclonal antibodies for an extended white blood cell (WBC) differential by flow cytometry. The aim of this study was to evaluate the usefulness of this approach in the routine workflow of a hematology laboratory. We compared a workflow chain comprised of a robotic blood preparation system (for antibody labeling), a flow cytometer, and data management software to the standard manual review of a blood film and evaluated the diagnostic quality, the turnaround time, and the labor needed for the two different approaches. The study on 1,973 samples was organized, firstly, to determine analytic thresholds and these settings were then validated. The flow cytometric data management software automatically validated 52% of the samples without significant numbers of false negatives. Of the remaining specimens, an operator validated a further 33% of the samples and 15% needed a manual microscopic review. These results were obtained in a mean timeline similar to the traditional microscopic manual review. Our study demonstrates, for the first time, the efficiency of a flow cytometer integrated into a WBC differential workflow in a routine hematology laboratory.