Performance characteristics of blast flagging on the Cell Dyn 4000 haematology analyser.

This study investigated the performance characteristics of blast flagging on the Abbott Cell Dyn 4000 (CD4000) haematology analyser. Our special interest was focused on the usability and prognostic value of the confidence fraction (CF), accompanying blast flagging. From our routine patient samples, 100 with blast flagging on the CD4000 were selected and examined microscopically for the presence of blasts. Blast flagging on the CD4000 resulted in a high number of false positive events. The results indicate that the blast flag confidence fraction (CF) of the CD4000 can be useful as a parameter for the prediction of the presence of blasts in samples with normal and increased white blood cell count. A model with criteria for blood smear examination following blast flagging was developed, using the blast flag CF combined with the WBC count. The model was tested and validated in a new set of 100 samples with blast flagging. Implementation of the criteria of the model resulted in a total reduction of the number of microscopic smear examinations of 45%, without losing clinically significant sensitivity.