An evaluation of blood smears made by a new method using a spinner and diluted blood

Blood smears were prepared with the use of a spinner, which rotated with a fixed velocity for a fixed time. All blood samples used for spun smears were diluted with a fixed ratio of buffered isotonic saline solution. Distribution of cells in these smears was found to be random. The average number of cells per unit area was substantially uniform from place to place on the same slide and on multiple slides made with the smae sample. The distribution of leukocytes by type was also iniform. For different blood samples, the average number of cells per unit area in the smears correlated well with the measured cell concentrations per unit volume in the samples for leukocytes, erythrocytes and platelets. Leukocyte differential counts on replicate spun smears using the same bloods also agreed to within the sampling error. They similarly agreed with differential counts on pulled smears made from undiluted samples of the same bloods. With few exceptions, erythrocytic morphology on the spun smears was comparable to that on the good areas of pulled smears made with undiluted samples of the same bloods. Nearly all the spun smears were suitable for both viual and fully automated hematologic examination for leukocytes, erythrocytes, and platelets. This was true over nearly the whole area of each spun slide. In these ways this spinner method makes smears whose consistently high quality is little affected by either the properties of the blood sample or the skill of maker.