Automated counting of platelets on the Bayer ADVIA (TM) 120 analyser

Precise counting of platelets is difficult particularly in the low thromboc ytopenic range or when large platelets exist. The recently available Bayer ADVIA(TM) 120 analyser uses a method of counting platelets based on two dim ensional laser light scatter. We have evaluated this technique on an analys is of 217 peripheral blood samples and found significant differences in pla telet counts compared with values obtained by impedance technology, when th e causes of thrombocytopenia were due to peripheral platelet consumption. M oreover, such differences were more marked in those samples from severely t hrombocytopenic individuals with large platelets on the blood film. These d ifferences, which warrant further study, may have significant implications for the management of patients with very low platelet counts.