An evaluation of the Celloscope 401 electronic blood cell counter.

For counting erythrocytes the instrument was precise, with a mean coefficient of variation of 1.21%. Erythrocyte counts showed close agreement with results obtained on a Coulter A electronic counter of proven accuracy. When the Celloscope 401 was modified by the manufacturers to eliminate electrical interference from other laboratory equipment, satisfactory precision and accuracy for white cell counting was obtained. Using cetrimide diluent the coefficient of variation was 1.6% but when using saponin/saline diluent the coefficient of variation was 3.5%. For leucocyte counting there was close agreement between duplicate tests performed on the Celloscope 401 and the Coulter S. The instrument was capable of satisfactory precision and accuracy in platelet counting, provided that the sedimentation method was used to obtain a platelet-rich plasma. The best results were obtained if a two-step dilution was carried out with a first dilution in 10% EDTA and a second in 2.5 mM cocaine in water. Using this method the precision study indicated a coefficient of variation of 3.11%. Close agreement was obtained between platelet counts on the Celloscope 401 when compared with the results obtained either by phase-contrast microscopy or using another electronic counter. Allowing for predilution and duplicate counts on each sample, the rate of throughput was approximately 32 samples per hour. Throughout the test period, the instrument remained electronically and mechanically stable.