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Abstract

Background: The haematology analyser, Sysmex XN-9000, generates white blood cell count with varying scattering intensities and abnormal WBC flags like monocytosis/abnormal lymphocytes/blasts during a complete blood count (CBC) analysis. The objective of the study is to determine the predictive role of abnormal flags (monocytosis; blast/abnormal lymphocytes; atypical lymphocytes) along with variation of WDF scatter plot and comparing them with peripheral blood smears for diagnosing and differentiation of leukaemia.
 Methodology: This study was performed at Chughtai Lab, Lahore from July, 2023 till October, 2023. A total of 160 EDTA samples were run on Sysmex NX 9000. Parameters that were studied and compared were WBC count, absolute monocyte count, monocyte percentage, abnormal flags and WDF scattergram. The results were confirmed by microscopy. Data was analyzed by SPSS version 23.00. Mean±SD was calculated for the continuous variable. Frequency and percentage were calculated for categorical variables. Pearson coefficient was performed to assess the correlation between various hematological parameters. Logistic regression was performed to determine the predictive role of abnormal flags and WDF scatter plot patterns in diagnosing leukemia. A p-value of <0.05 was taken as significant
Results:
The CBC analysis by the instrument shows a good ability to detect true positive cases (sensitivity of 57.5%). Specifically, it has zero specificity and negative predictive value (NPV), meaning it cannot accurately identify true negatives, leading to a high false positive rate. Consequently, the instrument test cannot reliably rule out the condition when it gives a negative result, necessitating confirmatory testing with the gold standard i.e. microscopic examination of the peripheral smear.
Conclusion:
Relying solely on the flags generated by Sysmex XN 9000 does not warranty accurate diagnosis. Further, examining of the peripheral blood smear should be mandatory for the detection of suspicious cells whenever an abnormal flag is generated.
Key words: Automated hematology analyzer, Abnormal flags, Sysmex XN, Monocytosis, Atypical lymphocytes, WBC Flags