Hematology counters were first built in the 19th century based on the particle counting principle given by Wallace H Coulter in the late 1940s. The introduction of hematology counters revolutionized the performance and functioning of diagnostic laboratories. Till the 1980s most of the analyzers were giving 10 parameter results which included the three-part white blood cell differential. The hematology counters in current times have come a long way from what they were earlier. The development has happened in almost all components of reports which include the red cell parameters, platelet parameters, and WBC differential counts. The counting principle in almost all the hematology analyzers still remains the same Coulter principle.
Red Cell Parameters
Standard red cell parameters that were available in older analyzers include MCV, MCH, MCHC, RDW, and hematocrit. These parameters give a lot of information about the degree and broad types of anemia. Newer generation counters have much more information about hematopoiesis than what was available earlier. Most of the current generation counters give reticulocyte count and reticulocyte hemoglobin levels. Reticulocyte count and its indices are very good indicators of erythropoiesis and thus the bone marrow functioning. They are one of the very early indicators of bone marrow recovery following transplants and response to hematopoietic therapy. Many parameters like Ret-HE on XN series of Sysmex are now routinely being used to guide iron therapy in patients with kidney disease. Parameters like MSCV in Beckman Counters are being used to diagnose cases of hereditary spherocytosis.
Newer generation counters can now differentiate platelets and red cell or its fragments from each other. This has been possible in counters that perform platelet counts based on dye binding properties and are called optical platelets. Immature platelet fractions which these machines give is an indicator of marrow functions and can predict platelet count recovery, 2 days in advance in patients with dengue.
Gone are the days of the three-cell incomplete differential. Newer generation analyzers from almost all manufacturers give the five-part WBC differential along with nucleated cell counts and immature granulocyte counts. In addition, there are many research parameters that give a lot of information on individual cell (different type of leukocytes) size and cytoplasmic contents. These parameters give a lot of information like the prediction of sepsis, the presence of blasts and atypical cells in peripheral blood. The instruments like XN1000 have a separate channel for progenitor cell count which can give information on the adequacy of stem cell dose in hematopoietic transplants.
Many new generation analyzers offer automated rule-based slide making and staining features that help to reduce the overall turnaround time and better standard staining qualities of the blood film. Currently, we are using one such instrument, the XN-3000, at our institute. This feature is also available in other instruments like the one offered recently by Mindray.
Artificial Intelligence is the Future
Actually speaking this is not the future but a reality now. The series like CellaVision DM1200 series can a slide and focus on abnormal cells of interest. One can just review the slides sitting on a digital screen. Further advances in this field, can minimize human intervention even in the field of microscopy.