A hematology analyzer is a medical laboratory instrument that measures the cells in a blood sample automatically. It is best known for producing a complete blood count, or CBC, which helps clinicians screen for anemia, infection, inflammation, bleeding disorders, and blood cancers. Automated counting is important because blood contains millions of cells in a tiny volume, so manual counting would be slow and less consistent.
The analyzer turns a small tube of blood into reliable numerical results within minutes.
Inside the instrument, the sample is mixed, diluted, and divided into pathways for red blood cells, white blood cells, platelets, and hemoglobin testing. Many analyzers use electrical impedance, optical light scatter, fluorescence, or a combination of these methods to count and classify cells. The device converts cell signals into histograms, scatterplots, and calculated values such as hematocrit and mean corpuscular volume.
Abnormal patterns can trigger flags that tell a technologist to review the sample or examine a blood smear.
Key Facts
- Complete blood count, CBC, commonly reports RBC count, WBC count, platelet count, hemoglobin, hematocrit, and red cell indices.
- Electrical impedance counts cells by detecting changes in resistance as each cell passes through a small aperture.
- Optical scatter classifies cells because different cell sizes and internal structures scatter laser light in different patterns.
- Hematocrit can be estimated by Hct = RBC × MCV, when RBC is in millions/µL and MCV is in fL with unit conversion applied.
- Mean corpuscular hemoglobin is calculated by MCH = Hb × 10 / RBC, where Hb is in g/dL and RBC is in millions/µL.
- Mean corpuscular hemoglobin concentration is calculated by MCHC = Hb × 100 / Hct, where Hct is a percent.
Vocabulary
- Hematology analyzer
- An automated laboratory instrument that counts and characterizes blood cells in a patient sample.
- Complete blood count
- A common blood test that reports the numbers and properties of red blood cells, white blood cells, and platelets.
- Electrical impedance
- A counting method in which a passing cell changes electrical resistance as it moves through a tiny opening.
- Light scatter
- A measurement of how cells deflect laser light, which helps estimate their size, granularity, and type.
- Differential count
- The classification of white blood cells into types such as neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
Common Mistakes to Avoid
- Treating every analyzer flag as a final diagnosis is wrong because flags are warnings that require review, repeat testing, or smear examination.
- Confusing cell count with cell concentration is wrong because analyzers report cells per volume, such as cells/µL, not the total number of cells in the body.
- Ignoring sample quality is wrong because clots, hemolysis, underfilled tubes, or poor mixing can produce inaccurate counts.
- Assuming all white blood cells look the same to the instrument is wrong because classification depends on measurable differences such as size, internal complexity, staining, and fluorescence.
Practice Questions
- 1 A CBC reports RBC = 4.80 million/µL and MCV = 90 fL. Estimate the hematocrit percent using Hct = RBC × MCV / 10.
- 2 A patient has Hb = 14.0 g/dL and RBC = 5.00 million/µL. Calculate MCH using MCH = Hb × 10 / RBC.
- 3 An analyzer reports a platelet count that is very low and also shows a platelet clump flag. Explain why the laboratory should not immediately report the value without further review.