Visualized histogram of the test results of the three-part hematology analyzer
In today's routine examinations, CBC testing is performed using automated blood analyzers.
In addition to reporting RBC, PLT and WCB counts, the analyzer can measure oxyhemoglobin (HGB) and determine a range of other parameters such as mean cell volume (MCV), PLT width distribution and hematocrit (HCT), namely The ratio of red blood cells to plasma. Therefore, automated analyzers can provide much more information than manual counts.
The three-class instrument usually uses the principle of electrical impedance to divide leukocytes into granulocytes (mainly neutrophils, but also eosinophils and basophils), lymphocytes and intermediate cells (mainly neutrophils) according to cell size. monocytes, but also eosinophils)
The number of pulses produced is related to the number of cells, and the size of the pulses is related to the size of the cells.
Principles of electrical impedance changes produced by cells through measuring pores
In addition to electrical impedance, the five-class instrument uses the principle of flow cytometry to classify white blood cells into five major subpopulations based on cell size and complexity (granularity), neutrophils, lymphocytes, monocytes, eosinophils cells, and basophils (P3).
In a flow cytometer, cells are forced to flow through pores as individual individuals by sheath fluid, a fast-flowing diluent that surrounds a slow-moving sample (P4).
The laser beam travels through the sample, and as a cell passes through the sensing area, the light is scattered and measured by a photoconductor, which converts the light into electrical pulses. The number of pulses produced correlates with the number of cells, while light scattering is used to determine cell granularity, shape and size (P4)
P3. The test results of the five-part hematology analyzer are displayed in a scatter plot
P4
(A) Five-differentiated leukocytes detected by laser flow cytometry.
(B) Triangular laser scattering method, in which low-angle signal (about 1°~5°) represents cell volume information, medium-angle signal (about 7°~20°) represents cell nucleus information, and high-angle signal (about 90°) represents cell nucleus and cytoplasmic information.
About 3-part and 5-part hematology analyzer
Each WBC subtype provides information that is helpful in diagnosing blood-related conditions, but a three-class instrument provides clinicians with only partial information. With a simple three-division CBC, the neutrophil and lymphocyte counts will answer the question of whether it can be treated with antibiotics, and whether it is a bacterial or viral infection. However, for specialized hospitals, a five-class instrument can provide a more detailed and targeted assessment of blood status. For example, to differentiate between eosinophils and basophils from neutrophils, a white blood cell quintile must be performed. Therefore, the five-category instrument is usually more suitable for specialized or specialized hospitals (eg, oncology, or allergic diseases) because it can provide eosinophil and basophil counts.
In general, suspiciously abnormal results often require the use of microscopy to double-check the results obtained by the analyzer, regardless of the type of instrument. For this purpose, blood smears are usually counted manually in a laboratory by professional examiners. Based on the experience of many hematology laboratories in blood smear examination, the five-category analyzer can obtain more detailed information about blood status, which can greatly reduce the number of blood samples that need to be manually reviewed. Assuming that about 30% of the samples in a three-category instrument will give acceptable abnormal results and thus require a blood smear review, the more detailed information provided by a five-category instrument reduces this number to about 20%, lowering It reduces the manpower and time cost of the hospital.
Conclusion
In most cases, three-part and five-part hematology analyzers can make the same interpretation of results. Generally, three-class instruments have faster detection times and lower costs.
In the event of abnormal values, blood smear microscopy is still required, regardless of instrument type. While three-category instruments can provide results with good accuracy for routine screening, for abnormal samples, five-category results can improve the accuracy of results and reduce the number of manual blood smears.
Whether choosing a three-category or five-category instrument, what matters most is the analyzer's ability to detect and flag abnorma samples.
