MLSP HEMA

• Hematology

  The study of blood

  
• Hematology

  • Primarily deals with the cellular elements of the peripheral blood and bone marrow
  • Includes morphologic appearance, function, and disease of blood
  • The body's main fluid for transporting nutrients, waste products, gases, and hormones through the circulatory system
• Blood composition

  • Total blood volume in an adult is 5 to 6 liters or 7 to 8% of the total body weight
  • Blood is analyzed in the form of whole blood, plasma, or serum

  
• Plasma

  The liquid portion of anticoagulated blood

  
• Serum

  The liquid portion of clotted blood

  
• Whole blood composition

  • Erythrocytes
  • Leukocytes
  • Platelets
  • Plasma

  
• Whole blood includes erythrocytes, leukocytes, platelets, and plasma

  
• When a specimen is centrifuged, leukocytes and platelets make up the buffy coat (small white layer of cells lying between the packed red blood cells and the plasma)

  
• Plasma


  Composed of 90% water and contains proteins, enzymes, hormones, lipids, and salts
• Serum


  Normally appears clear and straw colored (lacks fibrinogen group coagulation proteins)
• 45% of blood is composed of formed elements: RBC, WBC, Platelets

  
• Remaining 55% of blood is fluid composed of 90% water and 10% proteins, CHO, vitamins, hormones, enzymes, lipids and salts
• Blood characteristics

  • Color: arterial blood is bright scarlet red, venous blood is dark red
  • Viscosity (resistance to flow): thick and sticky fluid that normally flows with difficulty
  • Specific gravity: 1.055 to 1.065
  • pH: 7.35 to 7.45

  
• Most common hematologic procedures

  • Complete Blood Count (CBC)
  • Erythrocyte Sedimentation Rate (ESR)
  • Blood Indices
  • Reticulocyte Count

  
• Specimen collection and handling

  1. Venipuncture procedure

  2. Using syringe method

  3. Using evacuated tube system

  4. Butterfly collection
• Whole blood

  • The most common body fluid analyzed in the hematology section, a mixture of cells and plasma
  • Obtained by using a collection tube with an anticoagulant to prevent clotting of the sample

  
• Most tests performed in the hematology section require blood that has been collected in tubes with a lavender stopper that contain the anticoagulant ethylenediaminetetraacetic acid (EDTA)

  
• Immediate inversion of the EDTA tube eight times is critical to prevent clotting and ensure accurate blood counts
• Coagulation section

  • Sometimes a part of the hematology section, but in larger laboratories it is a separate section
  • Specimen: Plasma from light blue stopper tubes (sodium citrate)
  • The overall process of hemostasis is evaluated and this includes: platelets, blood vessels, coagulation factors, fibrinolysis, inhibitors, and anticoagulant therapy (heparin and Coumadin)

  
• Routine hematology procedures

  • Complete Blood Count (CBC)
  • Erythrocyte Sedimentation Rate (ESR)
  • Reticulocyte count
  • Peripheral blood smear - morphology

  
• Reasons for specimen rejection

  • Test order requisition does not match with the identification of the patient
  • Unlabeled specimen
  • Hemolyzed sample
  • Wrong specimen collection
  • Wrong tube
  • Clotted specimen for CBC
  • Contaminated specimen
  • Lipemic sample
• Complete Blood Count (CBC)


  • Most frequent blood test
  • Provides detailed information about the cells in the blood
  • Screening test for most diseases

  
• CBC measurements

  • WBC Count
  • Differential count
  • RBC Count
  • Hemoglobin
  • Hematocrit
  • Blood Indices
  • Platelet count

  
• Hematocrit


  Volume of packed red cells (VPRC)

  
• Microhematocrit method

  1. Fill heparinized capillary tube

  2. Seal with clay

  3. Centrifuge

  4. Read using direct reading device or caliper
• Sources of error in hematocrit count

  • Excess of anticoagulant
  • Undercentrifugation
  • Overcentrifugation
  • Improper use of reader
  • Wash out blood
  • Bubbles/spaces in the tube

  
• Hematocrit


  • Volume of packed RBCs that occupies a given volume of whole blood
  • Reported as percentage (%) or L/L
• Microhematocrit procedure

  1. Fill capillary tube approximately three-quarters full with anticoagulated blood

  2. Seal the end with clay and wax

  3. Centrifuge for 10,000 G for 5 minutes

  4. Determine hct using microhematocrit reader

  
• Hematocrit range: Male 40 - 54%, Female 35 - 49%, Neonates 48 - 68%
• Preparation of blood smear

  1. Collect before other samples to avoid platelet clumping

  2. Dermal puncture or venipuncture (EDTA within 1 hour of collection)

  
• Characteristics of a good blood smear

  • Smooth film of blood that covers approximately one-half to two-thirds of the slide
  • Does not contain ridges or holes
  • Has a lightly feathered edge without streaks
• Effects of technical errors in the slide

  • Uneven distribution of blood (ridges)
  • Holes in the smear
  • No feathered edge
  • Streaks in the feathered edge
  • Smear too thick and short
  • Smear too thin and long
• Peripheral blood smear (PBS)

  • Technique of preparation: wedge slide, coverslip
  • Staining: Wright's stain (eosin and methylene blue)

  
• Erythrocytes

  • Anuclear biconcave disks approximately 7.2 microns in diameter
  • Contain the protein hemoglobin to transport oxygen and carbon dioxide
  • Life span: 120 days
• Leukocytes


  • Provide immunity to certain diseases by producing antibodies and destroying harmful pathogens by phagocytosis
  • Normal number: 4,500 to 11,000 per µL of blood
  • Differential cell count determines the percentage of each type of leukocyte
• Neutrophils


  • The most numerous leukocytes (40-60%)
  • Provide protection against infection through phagocytosis
  • Called "segmented" or "polymorphonuclear cells"
  • Increases in bacterial infections
• Lymphocytes


  • The second most numerous leukocytes (20% to 40%)
  • Provide the body with immune capability by means of B and T lymphocytes
  • Has a large round purple nucleus with a rim of sky blue cytoplasm
  • The number increases in viral infections
• Monocytes


  • The largest circulating leukocytes (3% to 8%)
  • Act as powerful phagocytes to digest foreign material
  • The cytoplasm has a fine blue-gray appearance with vacuoles and a large, irregular nucleus
  • A tissue monocyte is known as a macrophage
  • The number increases in intracellular infections and tuberculosis
• Eosinophils


  • Have red orange granules, and the nucleus has only two lobes
  • Detoxify foreign proteins and increase in allergies, skin infections, and parasitic infections
• Basophils


  • The least common of the leukocytes (0% to 1%)
  • The cytoplasm contains large granules that stain purple-black
  • Release histamine in the inflammation process and heparin to prevent abnormal blood clotting