The
blood analyzer is currently the most commonly used test instrument for general clinical blood examinations. In the past, the manual microscope counting method was used. Due to the random errors in the operation process, the system errors of the experimental equipment and the inherent errors of the detection method, the accuracy of the experimental results of the microscope cell counting was greatly affected.
In the 1940s, Mr. Kurt, an American, invented and applied for a design patent for particle counting technology; in the early 1950s, electronic blood cell counters began to be used in clinical practice, ushering in a new era of blood cell analyzers. With the development of basic medicine, the application of high-tech, especially the use of computer technology, the analysis technology and clinical application of blood cell analyzers have made remarkable progress. Today's blood cell analyzers can generally provide more than a dozen to dozens of detection parameters for clinical disease diagnosis, differential diagnosis, treatment and efficacy observation. However, the following issues should be noted when using the instrument
1. Sample collection and the use of anticoagulants Specimen collection and the use of anticoagulants are key issues in quality control before the use of blood cell analyzers. They are very important, but people often do not pay attention to them. Blood sample collection and anticoagulants have a great impact on the accuracy of blood cell analysis results. For example, poor blood collection or poor anticoagulant effect often leads to a decrease in platelet count. At the same time, poor blood collection and the presence of small clots in the blood sample that are not easily found by the naked eye can lead to incomplete or complete blockage of the counting hole of the blood cell analyzer. Incomplete blockage of the counting hole is not easy to find, which can easily cause errors in the blood sample test results.
The main issues involved in sample collection are whether to use finger blood or venous blood? Use a vacuum blood collector or an ordinary syringe? Is it recommended to use venous blood and vacuum blood collection tubes to collect samples? . The most suitable anticoagulant for blood cell analysis is EDTA salt, which has little effect on blood cell morphology and platelet count. The 1993 document of the International Committee for Hematology and Standard Instruments (ICSH) recommends that EDTA-K2 be used as an anticoagulant for blood cell analysis, with a dosage of 1.5-2.2 mg/mL blood. At the same time, it should be noted that EDTA-dependent platelet aggregation can lead to pseudothrombocytopenia, which is mainly seen in tumors, autoimmune diseases, cor pulmonale, late pregnancy, liver disease, toxemia and some unexplained diseases. In the above cases, platelets should be counted using methods such as ammonium oxalate diluent.
2. Blood cell analyzer is a screening method for cell clustering. Blood cell analyzer has developed from a single electrical impedance technology to a fully automatic advanced instrument that combines multiple technologies including physics, chemistry, immunology, flow cytometry, etc., and the results of various blood cell analysis are more accurate and reliable. The degree of automation has developed from a single three-pressure clustering to a blood cell automatic analysis system, that is, the full automation of the whole blood cell count, reticulocyte count, peripheral blood push film and staining processes. However, to date, any blood cell analyzer can only be a screening method for blood cell clustering. In the presence of immature cells, the analysis results are unreliable and must be reviewed by manual microscope.
At present, many domestic hospital laboratories do not review or rarely conduct manual microscope review when blood cell counts and cell histograms are abnormal, resulting in inaccurate results and causing many medical complaints and disputes. For example, a female patient with fever went to a municipal hospital for treatment. The blood cell analysis results showed that the white blood cell count was 21.5×10/L, the hemoglobin was 98 g/L, and the blood cell histogram was abnormal. However, the laboratory department did not conduct a manual microscope review and issued a report. The clinician diagnosed the patient with upper respiratory tract infection and irregular menstruation based on the patient's fever, menorrhagia and other symptoms. After three months of treatment, there was no obvious effect. After examination at the next-level hospital, the white blood cell count had risen to 30.2×10/L, the hemoglobin had dropped to 89 g/L, and the blood cell histogram was abnormal. After manual microscope review, 35% of the peripheral blood was found to be immature cells, and the bone marrow puncture cytology was diagnosed as leukemia. It can be seen that over-reliance on instrument analysis results, on the one hand, reduces the requirements for professional knowledge of laboratory technicians and reduces their ability to understand cell morphology, and on the other hand, delays the diagnosis and treatment of patients.
3. Comparability of blood cell analysis results
At present, large and medium-sized hospitals generally have multiple blood cell analyzers of the same or different manufacturers, and the differences between the test results of the same items of the same specimen by detection systems with different models and reagents are sometimes far greater than the acceptable error range. Zhang Wen et al. compared the results of leukocyte determination by 7 different blood cell analyzers and found that the precision of the leukocytes detected by them met the clinical requirements, but the clinical acceptable performance evaluation was incomparable and corrective measures needed to be taken.
4. Conclusion
In order to improve the accuracy of the test results of blood analyzers, it is crucial to implement comprehensive quality control and calibration. The correct collection of blood samples and the rational use of anticoagulants are the key before analysis. For abnormal cell calculation results and abnormal histograms, manual microscopic review should be strengthened, the traceability system of blood cell analysis should be improved, and a standardized scheme that conforms to reality should be explored to ensure the consistency of analysis results, and some reference detection systems or laboratories should be established. Selecting qualified fresh whole blood to compare blood cell analyzers is a low-cost and highly applicable method to improve the comparability of test results of different blood cell analyzers.
