Effective and Practical Complete Blood Count Delta Check Method and Criteria for the Quality Control of Automated Hematology Analyzers

Background

Delta checks increase patient safety by identifying automated hematology analyzer errors. International standards and guidelines for the complete blood count (CBC) delta check method have not been established. We established an effective, practical CBC delta check method and criteria.

Methods

We assessed five delta check methods for nine CBC items (Hb, mean corpuscular volume, platelet count, white blood cell [WBC] count, and five-part WBC differential counts) using 219,804 blood samples from outpatients and inpatients collected over nine months. We adopted the best method and criteria and evaluated them using 42,652 CBC samples collected over two weeks with a new workflow algorithm for identifying test errors and corrections for Hb and platelet count.

Results

The median delta check time interval was 1 and 21 days for inpatients and outpatients (range, 1-20 and 1-222 days), respectively. We used delta values at 99.5% as delta check criteria; the criteria varied among the five methods and between outpatients and inpatients. The delta percent change (DPC)/reference range (RR) rate performed best as the delta check for CBC items. Using the new DPC/RR rate method, 1.7% of total test results exceeded the delta check criteria; the retesting and resampling rates were 0.5% and 0.001%, respectively.

Conclusions

We developed an effective, practical delta check method, including RRs and delta check time intervals, and delta check criteria for nine CBC items. The criteria differ between outpatients and inpatients. Using the new workflow algorithm, we can identify the causes of criterion exceedance and report correct test results.

The possibility of automatic capillary blood testing in routine blood tests: an evaluation of the automatic mode of the Mindray BC-7500 CRP Auto Hematology Analyzer for capillary blood testing

Background

Capillary blood is a common specimen type used for infant blood routine tests. Until now, this specimen type could only be tested with the manual mode in hematology analyzers. Manual sample mixing and loading increases the amount labor force and can be more easily affected by human factors. This study was designed to investigate the proficiency of the automatic mode of the Mindray BC-7500 CRP Auto Hematology Analyzer for capillary blood testing.

Methods

The complete blood count (CBC) results for capillary blood were compared between the automatic and manual modes. Special types of samples, including samples with high or low volume, thalassemia red cells, high fibrinogen, high hematocrit (HCT), or high triglyceride levels, were compared and evaluated. The intraclass correlation coefficient (ICC) was used to define the agreement between the 2 modes. The industry standard Analytical Quality Specifications for Routine Tests in Clinical Hematology (WS/T 406-2012), published by the National Health Commission of China, was used to evaluate the correlation between the results from the 2 modes.

Results

There was good correlation between the automatic and manual modes for every type of sample, and the ICCs were all higher than 0.9. Except for high HCT or high triglyceride samples, there were no differences found between the 2 modes based on the WS/T 406-2012 standard.

Conclusions

This new automatic mode utilized in the Mindray BC-7500 CRP Auto Hematology Analyzer for capillary blood yielded the same results as the manual mode except in the case of samples with high HCT or triglycerides. Capillary blood might be routinely tested automatically with hematology analyzers in the near future, which might reduce the labor required and improve standardization.

Clinical performance testing of the automated haematology analyzer XN-31 prototype using whole blood samples from patients with imported malaria in Japan

Background

The automated haematology analyzer XN-31 prototype (XN-31p) is a new flow cytometry-based device developed to measure the number and the ratio of malaria-infected red blood cells (MI-RBC) with a complete blood count (CBC). The XN-31p can provide results in about one minute and also can simultaneously provide information on the malaria parasite (Plasmodium) species. In this study, clinical testing of the XN-31p was performed using blood samples from patients with imported malaria in Japan.

Methods

Blood samples were collected from 80 patients who visited the hospital of the National Center for Global Health and Medicine, Tokyo, Japan, for malaria diagnosis from January 2017 to January 2019. The test results by the XN-31p were compared with those by other standard methods, such as microscopic observation, rapid diagnostic tests and the nested PCR.

Results

Thirty-three patients were diagnosed by the nested PCR as being malaria positive (28 Plasmodium falciparum, 2 Plasmodium vivax, 1 Plasmodium knowlesi, 1 mixed infection of P. falciparum and Plasmodium malariae, and 1 mixed infection of P. falciparum and Plasmodium ovale), and the other 47 were negative. The XN-31p detected 32 patients as “MI-RBC positive”, which almost matched the results by the nested PCR and, in fact, completely matched with the microscopic observations. The ratio of RBCs infected with malaria parasites as determined by the XN-31p showed a high correlation coefficient of more than 0.99 with the parasitaemia counted under microscopic observation. The XN-31p can analyse the size and nucleic acid contents of each cell, and the results were visualized on a two-dimensional cytogram termed the “M scattergram”. Information on species and developmental stages of the parasites could also be predicted from the patterns visualized in the M scattergrams. The XN-31p showed a positive coincidence rate of 0.848 with the nested PCR in discriminating P. falciparum from the other species.

Conclusions

The XN-31p could rapidly provide instructive information on the ratio of MI-RBC and the infecting Plasmodium species. It was regarded to be of great help for the clinical diagnosis of malaria.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04247-x.

Unusual Morphological and Automated Hematology Analyzer Features in 3 Cases of B-cell Malignancy-associated Type I Cryoglobulinemic Vasculitis

Type I cryoglobulins are monoclonal immunoglobulins produced due to underlying hematological malignancy. Cryoglobulins spontaneously precipitate from serum and plasma at low temperatures and become soluble again on rewarming to 37 °C. Processing of blood at temperature lower than 37 °C in the laboratory may cause precipitation of cryoglobulins resulting in interferences in the automated cell counter analysis. We report three patients with cryoglobulinemic vasculitis wherein each case had different morphology of cryoglobulin precipitates on peripheral blood film, like needle shaped bluish-gray crystals, amorphous weakly basophilic extracellular deposits extraneously indenting red blood cells and basophilic neutrophilic inclusions respectively. The effect of cryoglobulins on two technologically different automated cell counters based on principles of impedance, Volume-Conductivity-Scatter (VCS) and fluorescence flow cytometry was assessed. This case series provides interesting insight into the varying morphological features of cryoglobulins on May-Grunwald-Giemsa stained blood films and interference caused by cryoglobulins in different automated cell counter analysis resulting in pseudo-leucocytosis, pseudo-thrombocytosis, abnormal histograms and scatterplots. Identification of these hematologic abnormalities and artifacts induced by cryoglobulins is necessary since it may be the first clue leading to the timely diagnosis of cryoglobulinemia and hence the underlying hematological malignancy, as in our cases.

A comparison of Sysmex-XN 2000 and Yumizen H2500 automated hematology analyzers

A complete blood count is a highly automated laboratory test. The use of highly advanced measurement methods increases the accuracy and sensitivity of the determination of individual hematological parameters, especially in the case of white blood cells differentiation. Therefore, it is necessary to make comparative analyses, which involve performance of the analyzers used in daily work. The aim of the study was to indicate whether the results obtained using two compared analyzers show significant differences.

Materials and methods

In this study a comparative analysis of 241 peripheral blood samples from adult patients was performed. The complete blood count results were obtained using two automated hematology analyzers: Sysmex XN-2000 and Horiba Yumizen H2500. The Passing-Bablok regression method and Bland- Altman analysis were also used to evaluate the results received for both analyzers.

Results

Statistically significant differences were found for four hematological parameters: eosinophil count, immature granulocytes, mean corpuscular hemoglobin concentration (MCHC) and platelet distribution width (PDW). The P value for MCHC was 0.01. Sysmex XN-2000 and Horiba Yumizen H2500 also showed disagreement in plate platelet distribution width (PDW) (P ​= ​0.04). For other parameters both analyzers showed good agreement.

Conclusion

Based on the results of the study, it was shown that there are significant differences in the measurements of hematological parameters between compared analyzers.

Mindray SF-Cube technology: An effective way for correcting platelet count in individuals with EDTA dependent pseudo thrombocytopenia

Several strategies are applied to determine the precise platelet count in individuals with ethylenediaminetetraacetic acid dependent pseudo thrombocytopenia (EDTA-PTCP) caused by in vitro aggregation of platelets in daily laboratory practice. None of them proves optimal for routine purposes. Thus, Mindray has developed the SF-Cube technology coupled with the CDR mode in the Mindray hematology analyzer to overcome the problem of EDTA-PTCP. With Mindray SF-Cube technology, platelet aggregates dissociate effectively and platelets are correctly counted in the CDR mode without pre-analytical management. In our studies, the EDTA-PTCP blood samples when analyzed with the CDR mode of Mindray BC-6800 plus analyzer, yield a markedly higher platelet count compared to those obtained with PLT-I on Sysmex XN-9000 hematology analyzer. We conclude that in patients with known or suspected EDTA-PTCP Mindray SF-Cube technology is a straightforward and effective way of determining the platelet count in EDTA-anticoagulated blood.

Investigation of morphological changes for the discrimination of nucleated red blood cells and other leukocytes in Sysmex XN hematology analyzer scattergrams using transmission electron microscopy

Background

The WNR channel of the XN-Series automated hematology analyzer (Sysmex) counts white blood cells (WBCs) and simultaneously performs a differential counting of basophils and nucleated red blood cells (NRBCs). The detection process involves exposing the cells to WNR-specific reagents containing an acidic detergent and a fluorescent dye and measuring the intensity of the forward scattered light (FSC) and side fluorescence light (SFL).

Method

We treated isolated peripheral WBCs and NRBCs with specific reagents and assessed the morphological changes in NRBCs and each leukocyte type using transmission electron microscopy (TEM).

Results

The results from a flow cytometer (FCM) showed that, after exposure to the reagents, basophils appeared on the highest FSC and SFL areas compared to other leukocytes on the WNR scattergram. Owing to the hemolysis of reticulocytes and erythrocytes, NRBCs that survived the reagent treatment could be distinguished by their lower intensity than those of the other leukocytes on the WNR scattergram. We investigated the significance of the relationship between the TEM and FCM results after the reagent treatment.

Conclusion

We confirmed that the WNR channel differentiates the blood cells on the WNR scattergram based on differences in the amount of residual cytoplasm and nucleic acids.

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The WNR channel of the XN-Series counts WBCs and simultaneously performs a differential count of basophils and NRBCs.

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Basophils had the highest scattered light and fluorescent intensities after WNR treatment on a flow cytometer scattergram.

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NRBCs survived treatment with the WNR reagents had a lower intensity on the FCM scattergram than those of other leukocytes.

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TEM revealed that the WNR channel can differentiate blood cells based on the amount of residual cytoplasm and nucleic acids.

Evaluation of the LH780 hematology analyzer for detection and therapeutic monitoring of malaria: Cross-reactivity with nucleated RBCs

We evaluated the diagnostic usefulness of the LH780 Coulter blood cell counter for detection and therapeutic monitoring of malaria including cross-reactivity with nucleated RBC (NRBC) samples. A total of 405 patients (43 patients with Plasmodium vivax malaria and the control group of 120 healthy subjects, 111 patients with fever, and 131 patients with NRBCs) were analyzed with routine CBC using the LH780. We analyzed the CBC results according to three selected parameters: an abnormal peak in the WBC histogram before 35fL, the presence of red dots in the nonwhite cell zone of 2D WBC Diff Dataplot, and platelet-related flags suggesting platelet clumps or giant platelets. Of the 43 malaria samples collected at diagnosis, an abnormal peak (≥2.2mm) was present in 93.0% (95% confidential interval (CI), 80.9-98.5%). Of all samples, 97.7% (95% CI, 87.7-99.9%) exhibited red dots, and platelet-related flags were observed in 81.4% (95% CI, 66.6-91.6%). The specificity of these three selected parameters was 83.1% (95% CI, 78.9-86.9%), 77.3% (95% CI, 72.7-81.6%), and 90.1% (95% CI, 86.5-92.9%), respectively. The abnormal peak (≥2.2mm) showed moderate correlation with parasite level (r=0.79). The three selected LH780 parameters were useful for identifying malaria in healthy subjects and febrile patients, but unsatisfactory for discriminating malaria in NRBC samples. The parameters showed a substantial proportion of false positives in the NRBC group, ranging from 26.7% to 49.6%. Therefore, microscopic confirmation will be necessary for application of these parameters for malaria screening and treatment monitoring.

Clinical significance of cell population data (CPD) on Sysmex XN-9000 in septic patients with our without liver impairment

BACKGROUND

This study evaluated the clinical significance of cell population data (CPD) parameters obtained on Sysmex XN-9000 in septic patients admitted to intensive care unit (ICU) and stratified according to liver function.

METHODS

The study population consisted in 84 patients, 44 of whom did not develop sepsis (NS), whereas the remaining 40 developed sepsis (SE) (n=24) or septic shock (SS) (n=16). Two hundred ostensibly healthy blood donors [healthy subjects (HS)], undergoing routine blood testing before a regular blood donation, were studied.

RESULTS

Except for neutrophils and lymphocytes cell size (NE-FCS and LY-Z), all other CPD values were significantly different in ICU patients compared to HS. Neutrophils and monocytes fluorescence intensity (NE-SFL and MO-X) values were significantly higher in SS compared to sepsis and not develop sepsis patients. The value of many parameters was also different according to liver function. Overall, MO-X and neutrophils fluorescence intensity (NE-SFL) exhibited the best performance for diagnosing sepsis in all patients (AUC, 0.75 and 0.72), as well as in those with (AUC, 0.95 and 0.89) or without (AUC, 0.72 for both) liver impairment. These parameters were also significantly correlated with Sequential Organ Failure Assessment (SOFA) score.

CONCLUSIONS

This study suggested that some novel CPD parameters (namely NE-SFL and MO-X) may provide useful information for diagnosis and management of sepsis.

Peripheral leukocyte anomaly detected with routine automated hematology analyzer sensitive to adipose triglyceride lipase deficiency manifesting neutral lipid storage disease with myopathy/triglyceride deposit cardiomyovasculopathy

Adipose triglyceride lipase (ATGL) deficiency manifesting neutral lipid storage disease with myopathy/triglyceride deposit cardiomyovasculopathy presents distinct fat-containing vacuoles known as Jordans' anomaly in peripheral leucocytes. To develop an automatic notification system for Jordans' anomaly in ATGL-deficient patients, we analyzed circulatory leukocyte scattergrams on automated hematology analyzer XE-5000. The BASO-WX and BASO-WY values were found to be significantly higher in patients than those in non-affected subjects. The two parameters measured by automated hematology analyzer may be expected to provide an important diagnostic clue for homozygous ATGL deficiency.

Underestimation of the coexistence of iron deficiencies and thalassemia minors: a single institution experience in Taiwan

Some physicians neglect the possible coexistence of an iron deficiency with a thalassemia minor and do not treat the iron deficiency accordingly. This motivated us to conduct this study. We retrospectively reviewed the records of 3892 patients who visited our clinics and had hemoglobin (Hb) electrophoreses performed in our hematologic laboratory from August 1, 2007 to December 31, 2012. The thalassemia minors were identified by characteristic complete blood count (CBC) parameters obtained from an autoanalyzer and Hb electrophoresis, and some cases were confirmed with molecular tests. Then, we checked iron studies [ferritin and/or serum iron with total iron-binding capacity (TIBC)] to determine the coexistence of an iron deficiency with a thalassemia minor and a response to iron, if such treatments were given. We found 792 cases with thalassemia minors, and excluded those without iron studies, with 661 cases as our sample. A total of 202/661 cases (31%) also had iron deficiencies. They had lower red blood cell (RBC) counts, Hb, and ferritin levels as compared to those thalassemia minor cases without coexistence of iron deficiencies. We concluded that the thalassemia minor patients did not have iron overload complications in our population. On the contrary, iron deficiencies commonly coexist in the clinical visits. We propose that if Hb < 11.5 g/dL in a case of thalassemia minor, one should screen for iron deficiency simultaneously. The sensitivity is 79.8% and the specificity is 82.6%. Therefore, physicians should be aware of this coexisting condition, and know how to recognize and treat it accordingly.

The instability of commercial control materials in quality control of mean corpuscular volume

BACKGROUND

Mean corpuscular volume (MCV) of stabilized whole blood used for quality control (QC) of hematology analyzers exhibits a tendency to increase during storage. The aim of this study is to evaluate the extent of biases over time with 3 most widely used control materials and to map out a strategy to overcome the data shift of MCV on daily QC practice.

METHODS

QC results of TESTPoint tested by ADVIA 2120i, e-CHEK tested by XE 2100, and 6C Cell Control tested by DxH 800 were analyzed.

RESULTS

MCV of all control materials showed a tendency to increase over time. By the fifth week, most of the materials showed biases larger than one standard deviation, with some exceeding a bias of four standard deviations.

CONCLUSIONS

Laboratories should apply appropriate QC strategies in MCV tests by considering their individual quality and efficiency requirements.

Contamination of patient blood samples by avian RBCs from control material during automated hematology analysis

OBJECTIVES

Atypical nucleated RBCs (NRBCs) found on several patient blood smears between 2010 and 2012 were noted to resemble avian RBCs. NRBCs are not normally found in the circulation beyond the neonatal period and may indicate hematologic disease, malignancy in the bone marrow, or other severe conditions. Our blood smears with unusual NRBCs did not contain other abnormalities that typically accompany NRBCs, such as immature cells or dysplastic granulocytes. To investigate this anomaly, we considered possibilities such as contaminated collection tubes and instrument problems. The Retic-C Cell Control used with the LH 750 Hematology Analyzer contains a mixture of human and avian RBCs.

METHODS

CBC count with differential tests were performed on blanks and routine laboratory samples run immediately after the Retic-C Cell Control on the LH 750 and LH 780 analyzers to recreate the conditions that might cause spillage into the next tube.

RESULTS

We experimentally reproduced the phenomenon of contamination of a subsequent tube with avian cells from a multiply punctured reticulocyte control tube.

CONCLUSIONS

We concluded that the NRBCs likely represented avian RBCs from the Retic-C Cell Control that had been introduced into the patient tubes.