IMPROVED AUTOMATED LEUKOCYTE COUNTING AND DIFFERENTIAL IN NEWBORNS ACHIEVED BY THE HEMATOLOGY ANALYZER CELL-DYN 3500(TM)

Automated leucocyte counts in newborns generated by the impedance prin ciple are artificially affected by the high osmotic resistance of some newborn RBC and possibly by the high normoblast numbers present durin g the neonatal period. Erroneously high WBC counts may result. The hae matology analyser CELL-DYN 3500(TM) (Abbott Diagnostika GmbH, Wiesbade n-Delkenheim, Germany) has two different channels for the WBC count, a n electrical resistivity (impedance) channel and a laseroptical channe l. In combination with facultative extended lysis of resistant RBC bef ore WBC count, this instrument is claimed to be very suitable for newb orn blood analysis. We measured the WBC count and differential of 165 blood samples from newborns and cord blood on the CELL-DYN 3500T(TM). Reticulocyte count and manual differential including normoblasts were determined. Furthermore, some technical aspects of neonatal blood anal ysis were evaluated: precision, cell stability, effect of incorrect bl ood-anticoagulant ratio of small blood collecting tubes. The internal decision making process of the CELL-DYN 3500(TM) selects the result ei ther from the optical channel (identifies and excludes normoblasts) or from the resistivity channel (eliminates resistant RBC). This instrum ent gives a reliable and accurate WBC count and differential of neonat al samples even in blood samples with normoblasts and lytic resistant RBC. The result given by the CELL-DYN 3500(TM) can be confirmed by a s ubsequent run in extended lyse mode.