54 B. D. HEDLEY ET AL. DXH 800 PERFORMANCE EVALUATION (<0.5 · 109/l). The DxH 800 does generate ﬂags; how- ever, the messages are more detailed than in previous analyzers and alert the operator to potential sample or enumeration issues. Manual review of these samples may still be necessary, depending on laboratory pol- icy, in order that accurate results are communicated to the treating physician. The heterogeneous morphology of NRBCs can lead to signiﬁcant problems when enumerating WBC with impedance technology. The ISLH method for correc- tion is dependent on manual review of suspect sam- ples identiﬁed by NRBC ﬂagging on a cellular analysis system. The number of NRBCs are then enumerated, expressed as the number present per 100 WBCs, and the WBC count is subsequently adjusted mathemati- cally. The assumption that all NRBCs have been included within the WBC count may or may not hold true. NRBCs smaller than the WBC threshold will not have been included in the WBC count, whereas those greater than the threshold have the potential to have been. Manual correction for all the NRBCs seen by morphological review may lead to over correction of the WBC count. The DxH 800 uses advanced algo- rithms and the collection of ten times more data than previous analyzers to determine the ‘signature posi- tion’ without the need for a nuclear dye (increasing cost) or rerunning (increasing turn around time) as with other commercially available analyzers. One of the most beneﬁcial enhancements provided by the DxH 800, in our estimation, is the appropriate correction of red cell parameters in the presence of extreme leukocytosis. Automated and accurate correc- tion of RBC parameters will allow for more rapid turn around times in patients with extreme leukocytosis, forgoing the need for manual manipulation and the potential for introduction of error. The data in this study demonstrate that both test and comparator instruments (DxH 800 and LH 780, respectively) provide accurate PLT results and in the case of the DxH 800, when the counts are extremely low (<10 · 109/l). A negative bias across the range of PLT values above 50 · 109/l explains the low P values seen in Table 2. When PLTs in the critical range 0– 50 · 109/l were compared, there was no bias noted between the FCM and DxH 800 values. Cellular debris (and other substances) and large PLTs may be included or excluded in the PLT count and depending on their proportions the machine may generate a ‘ﬂag’. Generation of the ﬂag requires veriﬁcation by another method (either manual chamber count or FCM), with the manual chamber count carrying a high coefﬁcient of variation and FCM being impracti- cal or unavailable for many laboratories. (Hanseler, Fehr & Keller, 1996; Harrison et al., 2000). The DxH 800 boasts a signiﬁcant increase in the amount of information (256 channels) collected on each sample. This combined with advances in algorithms and infor- mation sharing between other modules (potential interference detected in another parameter, e.g. micr- ocytic RBC) help to reduce ﬂagging and better enu- merate PLTs at low levels. The accurate enumeration of low numbers of PLTs is important because throm- bocytopenia may be a dose-limiting factor for cancer patients undergoing chemotherapy and also serves a trigger for PLT transfusion therapy (Navarro et al., 1998). The CSLI and ISLH guidelines have established the lower limit for detection of NRBCs to be 1 per 100 WBCs. We observed a small negative bias, ()0.6), in NRBC enumeration on the DxH 800 over the range from 0 to 60 NRBCs compared to FCM (FCM). It should be noted, however, that below 10 NRBCs the bias seen was very small. The ability to enumerate NRBCs at the lower limit is now available on the new DxH 800, representing a signiﬁcant improvement. The DxH 800 represents an improvement to previ- ous analyzers with an extended range for key parame- ters, better sensitivity in the low range, as well as the accurate detection and enumeration of NRBCs at counts >1/100 WBCs. The reduction in ﬂagging rate of the NRBC parameter should translate into reduced numbers of technically demanding and time-consum- ing blood ﬁlm reviews. The automatic correction of RBC parameters in extreme leukocytosis eliminates the need for operator intervention and should signiﬁ- cantly reduce the turn around time of severely abnor- mal results. These enhancements are afforded without the requirement of rerunning the sample or additional reagents. A C K N O W L E D G E M E N T S The authors thank Mr. Patrick O’Neil and Mrs. Maritza Lavernia for their assistance with this study. 2010 Blackwell Publishing Ltd, Int. Jnl. Lab. Hem. 2011, 33, 45–56