Implementing a routine flow cytometry assay for nucleated red blood cell counts in cord blood units

Noninvasive prenatal diagnosis targeting fetal nucleated red blood cells

Noninvasive prenatal diagnosis (NIPD) aims to detect fetal-related genetic disorders before birth by detecting markers in the peripheral blood of pregnant women, holding the potential in reducing the risk of fetal birth defects. Fetal-nucleated red blood cells (fNRBCs) can be used as biomarkers for NIPD, given their remarkable nature of carrying the entire genetic information of the fetus. Here, we review recent advances in NIPD technologies based on the isolation and analysis of fNRBCs. Conventional cell separation methods rely primarily on physical properties and surface antigens of fNRBCs, such as density gradient centrifugation, fluorescence-activated cell sorting, and magnetic-activated cell sorting. Due to the limitations of sensitivity and purity in Conventional methods, separation techniques based on micro-/nanomaterials have been developed as novel methods for isolating and enriching fNRBCs. We also discuss emerging methods based on microfluidic chips and nanostructured substrates for static and dynamic isolation of fNRBCs. Additionally, we introduce the identification techniques of fNRBCs and address the potential clinical diagnostic values of fNRBCs. Finally, we highlight the challenges and the future directions of fNRBCs as treatment guidelines in NIPD.

Improving the efficiency of the autoverification workflow for nucleated red blood cell reporting in the hematology laboratory

OBJECTIVE

Although the microscopic manual count is considered the standard method for NRBC enumeration, modern hematology analyzers can perform this task automatically with reliable accuracy and efficiency. This study aims to evaluate the diagnostic performance of the Sysmex XN hematology analyzer and to construct the optimal workflow for accurate and efficient NRBC reporting.

METHODS

Specimens containing different levels of NRBC were included. Analytical performance was evaluated via method comparison with flow cytometry (FCM) and manual count (MC). Clinical sensitivity was analyzed by ROC analysis using manual count as the standard method.

RESULTS

Correlation study of %NRBC with FCM and MC demonstrated an r value of 0.925 (95% CI 0.905 to 0.942) and 0.990 (95% CI 0.987 to 0.992) with a mean difference of -0.8 (95%CI: -6.7 to +5.0) and +0.50 (95% CI: -6.7 to +7.7), respectively. When the automated NRBC count was equal to zero and >0.07 × 10⁹ /L, the false-negative rate and false-positive rate were 100%, respectively; hence, manual slide review could be omitted. A false-positive rate of 72.7% was noted in specimens containing NRBC count less than 0.07 × 10⁹ /L.

CONCLUSION

The Sysmex XN can help improve the efficiency of NRBC enumeration owing to its accuracy, rapidity, and automation. However, further studies are required to improve the accuracy of detection in specimens containing a very low level of NRBC.

Automated nucleated red blood cell count using the Mindray BC-6800 hematology analyzer

INTRODUCTION

In current laboratory practice, obtaining a nucleated red blood cell (NRBC) count by manual microscopy (MM) is a laborious and time-consuming process. Modern hematology analyzers based on different technologies and methods have variable accuracies when determining NRBC counts. The aim of this study was to compare NRBC counts acquired by an automated Mindray BC-6800 analyzer (BC-6800), a flow cytometry (FC) reference method, and traditional MM.

METHODS

A hundred EDTA samples with initial NRBC flags from the BC-6800 were included. FC was used as a reference method to correlate the NRBC count with BC-6800 and MM counts. In addition, the performance of the Mindray SC-120 analyzer for preparing automated blood films for manual NRBC counting was compared to that of manually prepared blood films.

RESULTS

The NRBC counts obtained with the BC-6800 and MM vs the reference method were highly correlated (r = .994 and .989, respectively). However, the BC-6800 showed a lower bias than MM when compared with FC (0.3 × 10⁹ /L and -6.0 × 10⁹ /L, respectively). NRBC counts obtained using the automated Mindray SC-120 films were comparable to manually prepared films.

CONCLUSION

The Mindray CAL8000 automated hematology system, which is composed of the BC-6800 and the SC-120, yields a precise NRBC count and can replace the traditional MM method for obtaining accurate and reproducible NRBC counts in high-value samples, such as patient monitoring samples used to determine the necessity of transfusion therapy in thalassemia patients. Moreover, this method offers several advantages, including a faster turnaround time, labor savings, and cost effectiveness.