Hematology analyzers generate suspect flags that involve microscopic reviews to confirm the presence of pathologic cells. This study investigated the reliability of the blast flag in a side-by-side evaluation of 3 Sysmex XE-5000 instruments (Sysmex, Kobe, Japan). The repeatability of the Q values reported by each instrument for 10 replicates of the same blood samples was low (intraclass correlation coefficient [ICC] values, 0.62-0.74). The reproducibility of the Q values obtained by analyzing 408 samples on all 3 instruments was reasonable (ICC value, 0.85). In addition, a systematic difference was observed among the instruments in the level of reported Q values. With cutoff commonly being 100, the observed reproducibility of the blast flagging among the instruments was evaluated as poor (κ = 0.73). Based on the observed low performances, we question the usefulness of the Q value as a predictor of blasts and whether a blast flag reported by the XE-5000 is sufficient as a criterion for performing a microscopic review.

The preclassification feature alone is sufficient to verify the absence of blasts in flagged samples. When the preclassification feature detects blasts, the finding has to be verified or reclassified by an experienced technologist. However, the use of CellaVision™DM96 in the follow-up of blast reports has to be questioned due to the finding of false-negative samples in the preclassification feature, but also after re-classification, compared to manual slide review.

A complete blood cell count that includes a differential count of white blood cells (WBCs) is an important test to detect hematology abnormalities and to monitor patients' disease status. Most hematology analyzers identify samples with suspect abnormal cells and report the results by pathology flags. The diagnostic ability of a flag is a function of the underlying technology, and the computerized algorithms designed to evaluate the data. Concerning the presence of blasts, the Sysmex XE and XN analyzers report the flag "Blasts?" and "Blasts/ Abn.Lympho?", respectively. On the XE analyzers, the flag "Blasts?" is derived by a cluster analysis of scatterplots from the differential (DIFF) and the immature myeloid information (IMI) channel. On the XN, the flag "Blasts/Abn Lympho?" is triggered based on information from the white blood cell differential channel (WDF channel). The flag "Blasts?" indicates the possible presence of myeloblasts, and the flag "Blasts/Abn Lympho?" indicates the possible presence of blasts not specified by lineage and/or abnormal lymphocytes. 1,2 Despite the continuous improvement of the hematology analyzers, the flags are subject to ambiguities that require further examination. Several Abstract Introduction: The aim of the present study was to evaluate the diagnostic ability of blast flags generated by Sysmex instruments (XE/XN) by comparing with immunophenotyping by flow cytometry (IFCM). Additionally, the ability of manual microscopy and CellaVision DM96 (pre-and reclassification) to predict the presence of "true" blasts was investigated. Methods: Blood samples (n = 240) with suspect pathology flags reported by the XE were collected from the daily workload and examined by the XN, by manual microscopy, by CellaVision DM96 and by IFCM (CytoDiff Panel). Results: The ROC analysis for blasts showed an area under the curve of 0.64 ("Blasts?") (XE), 0.57 ("Blasts/Abn Lympho?") (XN), 0.75 (CellaVision preclassification procedure), 0.78 (CellaVision reclassification procedure), and 0.81 (manual microscopy). The sensitivity of blast detection varied between the methods from 0.41 (XE) to 0.90 (XN), and the specificity varied from 0.17 (XN) to 0.95 (CellaVision reclassification). Conclusions:The CellaVision reclassification procedure has a diagnostic ability for predicting blasts close to that of manual microscopy. The blood smear methods show a notable number of false negative results. The Sysmex XN reported a higher rate of true positive blast flags than the XE. Taken together, the CytoDiff method could be a useful alternative to smear examination to correctly identify blasts. K E Y W O R D S blast flag, CellaVision, CytoDiff, flow cytometry, Sysmex hematology instruments | 339 EILERTSEN ET aL.