Accuracy of Hematology Analyzers

In laboratories, we often find different brands of hematology analyzer machine also known as blood cell analyzer. This medical device has become part of clinical examination. It helps laboratory scientist to do white blood cell counts, complete blood counts, reticulocyte analysis and coagulation test. but how accurate and precise hematology analyzer compared to manual procedure. A study was conducted in Shanghai, China to compare maximum coefficients of variation from 3 main manufacturers (Sysmex, Beckman Coulter and Abbott). The objectives were to research on the accuracy of automated hematology analyzers of various types from different manufacturers and to observe the deviation among these instruments. Fresh anticoagulated blood from healthy donors on 115 hematology analyzers in 114 different hospitals were determined. The result was the maximum coefficients of variation (CVs. %) among instruments of three main manufacturers (Sysmex, Beckman Coulter and Abbott) of red blood cell count (RBC), hemoglobin (Hgb), hematocrit (Hct), white blood cell count (WBC) and platelet count (Plt) were 3.2%, 3.8%, 3.6%, 9.3% and 10.8%, respectively. The maximum deviations among these parameters of different instruments were 0.74%, 1.65%, 5.45%, 7.06% and 18.55%, respectively. By improving laboratory quality management, the results of hematology analyzer determination may be more reliable than manual methods. The difference among various manufacturers was very small about RBC, Hgb, Hct, WBC and Plt the results from all kinds of instruments will tend to be comparable. According to American Journal of Clinical Pathology, Measurement of platelet counts using automated hematology analyzers is usually quite precise and accurate. However, the accuracy of automated platelet counts can be compromised when measuring very low platelet counts or in the presence of interference from non-platelet particles or platelet abnormalities. Recent studies, mainly focusing on the counts of low levels of platelets, demonstrated that automated counts were not as accurate in severely thrombocytopenic samples.These findings are of concern because current clinical guidelines lowered the prophylactic platelet transfusion threshold to 10 × 109/L for patients without additional risk factors. In addition to this limitation of the technology, automated platelet counts can be inaccurate even at normal or high platelet ranges owing to the characteristics of blood specimens, eg, in specimens with a substantial amount of interfering particles, including WBC fragments, RBC fragments, immune complexes, bacteria, lipid droplets, or protein aggregates. WBC fragments can cause the spurious elevation of platelet counts in patients with acute leukemia at diagnosis and during chemotherapy.In 1 study, platelet-like fragments of leukemic blasts were observed in 25% of acute leukemia cases. In addition, granulocyte fragments or microorganisms are possible sources of platelet count overestimation in septic patients. RBC fragments, which are often observed in patients with malignancies as part of microangiopathic processes, are also recognized as a cause of erroneous platelet counts. To improve the accuracy of platelet counting and the feasibility of comparing platelet counts between analyzers, the International Council for Standardization in Haematology (ICSH) and the International Society of Laboratory Hematology (ISLH) proposed flow cytometry analysis of monoclonal antibody–labeled platelets and the calculation of platelet counts from the platelet/RBC ratio as a new international reference method (IRM). After the establishment of the IRM, multicenter studies comparing counting methods in platelet concentrates were performed. These studies identified considerable variation between the different counting principles and between different instruments using the same counting principle; this variability was suggested to be related to the increased proportion of activated small platelets. When platelets are activated, they become spherical with a hypogranular cytoplasm and release small particles. This may lead to the erroneous detection of platelets when using automated hematology analyzers owing to their deformed morphology. Patients with acute leukemia or disseminated intravascular coagulation (DIC) have an increased risk not only for interference from nonplatelet particles but also for counting errors due to platelet activation because platelet activation is inevitable during the course of a disease in which high levels of thrombin are generated and many inflammatory cytokines induce platelet activation. Recognizing erroneous results of automated platelet counts in these situations is especially critical for a consistent decision in the diagnosis of DIC and for clinical decision making regarding transfusion. The platelet count is an indispensable parameter in the DIC scoring system proposed by the International Society on Thrombosis and Haemostasis Sub-Committee of the Scientific and Standardization Committee on DIC, in which platelet counts of less than 100 × 103/μL (100 × 109/L) and less than 50 × 103/μL (50 × 109/L) would score 1 and 2 points, respectively.