of improving the reportable range of this new instrument (see Table 1), especially in the presence of interference. The system comprises a data management module running on Microsoft Windows XP which can store a database of up to 40 000 patient results with graphical representation via a touch screen. Overall, the DxH 800 cellular analysis system has a smaller foot- print that the predicate LH 780 analyzer. A digital bar code reader with 2D bar code capability is used for load- ing control materials and reagents which should help in reducing errors in instrument setup and accurately tracking reagent use. The capacity is twenty separate ﬁve-tube cassettes with a maximal automated through- put of 100 samples per hour. The aspiration volume in both open/closed vial modes has been reduced to 165 ll of sample allowing for small volume samples to be run (e.g. pediatric samples). A new ﬂow cell design supports additional light scatter measurements enabling enhanced data acquisition for the WBC differential, reticulocyte, and NRBC analyses. This enhanced data collection allows the DxH 800 to collect 10 times more information on each sample when compared to predi- cate analyzers. These advances allow the DxH 800 to accurately determine a WBC count even in the pres- ence of interference. A new feature on the DxH 800 is the appropriate correction of RBC parameters in the presence of leukocytosis [uncorrected (UWBC) 11 · 109/l]. Hemoglobin is corrected when the UWBC count is 11 · 109/l and if the UWBC count is 140 · 109/l then the RBC count is automatically cor- rected. The MCV, red cell distribution width (RDW), and red cell distribution width standard deviation (RDWSD) are corrected only if there is evidence that the WBC events are negatively impacting the RBC his- togram. The accuracy of the DxH 800 was determined by analyzing samples on a predicate analyzer (LH 780) and with a select group of parameters, by a ﬂow cyto- metric reference method (FCM). Flagging rates were determined by comparing data from the DxH 800 and predicate LH 780 analyzer. LH 780 The LH 780 is a fully automated random access ana- lyzer with a throughput capability of 110 samples per hour (CBC/DIFF only). The analyzer generates a CBC, with a corrected WBC in the presence of interference, a WBC differential, a reticulocyte percentage and 2010 Blackwell Publishing Ltd, Int. Jnl. Lab. Hem. 2011, 33, 45–56 B. D. HEDLEY ET AL. DXH 800 PERFORMANCE EVALUATION 47 number, as well as a NRBC percentage and number. The WBC count is derived by an impedance technol- ogy similar to that of the DxH 800. Classiﬁcation of WBCs is performed by threshold size discrimination (>35 ﬂ). Interfering particles such as NRBCs, nonlysed red cells, giant PLTs, or PLT clumps, or fragmented cells which hover near this threshold potentially may be included in the WBC count. If any interfering par- ticles are detected, the LH 780 generates a suspect message ‘cellular interference’ and will automatically correct the WBC count if necessary. Enumeration of the NRBC count is performed when particles are detected in the NRBC signature positions of both the WBC and the differential plots. Manual RBC indices correction The standard laboratory method involved centrifuga- tion of the sample and preparation of a concentrated red blood cell suspension, free of WBCs. The following calculations were applied; the corrected RBC count was determined by subtraction of the WBC count from the original RBC number of the neat sample. A corrected Hct was determined by multiplying the true MCV, derived from the RBC suspension, by the cor- rected RBC and dividing by 10. Finally, a corrected Hb was calculated by multiplying the true MCHC, derived from the RBC suspension, by the corrected Hct. Daily operations Daily checks were performed each day as part of rou- tine startup procedures. Startup was performed to ensure that the ﬂuidics lines were purged of cleaning agent, and that the background counts, voltage read- ings, and reagent dates were within acceptable limits prior to data collection. Quality Control on all instru- ments was run daily to ensure that all instruments were operating within acceptable limits. Following daily operation, shutdown was performed ensuring appropriate cleansing of the ﬂuidic system. Coulter XL-MCL The ﬂow procedures were performed on a single laser four-color Beckman Coulter XL-MCL ﬂow cytometer. Alignment and calibration checks were performed daily.