Hematology

• Hematology


  The study/science of blood
• EDTA


  Chelates calcium, anticoagulant of choice for hematology cell counts and cell morphology
• Blood smear preparation


  Prepare within 2 hours
• Platelet satellitism


  Platelets adhere to neutrophils, decreasing automated platelet count
• Platelet satellitism


  Remedy: Repeat platelet count using citrate (Rodak: Platelet count x 1.1)
• EDTA


  Causes shrinkage of cells, decreases hematocrit and erythrocyte sedimentation rate
• EDTA inhibits fibrinogen-thrombin reaction and factor V is not stable in EDTA, so not for coagulation tests
• Modified Westergren ESR


  2mL EDTA + 0.5mL NSS/Citrate, ratio 1:4 (Anticoagulant-to-Blood)
• Citrate


  Preserves labile factors V and VIII, buffered 3.2% (0.109M) citrate, ratio 1:9 (Anticoagulant-to-Blood)
• Polycythemic patients


  Increased hematocrit, excess citrate decreases PT and APTT
• Remedy for excess citrate in polycythemic patients

  Reduce the volume of citrate, amount of citrate = [(100-Hct)÷(595-Hct)] x mL WB
• Oxalate


  Double/balanced oxalate (Ratio = 2:3) maintains cell structures, potassium oxalate shrinks cells, ammonium oxalate swells cells
• Heparin


  Inactivates thrombin, anticoagulant for osmotic fragility test, distorts cells and produces bluish background on Romanowsky's stain, inhibits thrombin and all stages of coagulation
• Order of draw (evacuated tube)

  • Sterile blood culture tube
  • Citrate (blue)
  • Nonadditive tube (red)
  • Heparin (green)
  • EDTA (lavender)
  • Fluoride (gray)
• Order of draw (syringe method)

  • EDTA
  • Other anticoagulated tubes
  • Nonadditive tube
• EDTA containing tubes


  • Lavender
  • Pink
  • White
  • Royal blue
  • Tan
• Skin puncture sites


  • Fingertips
  • Earlobe: less admixture with tissue juice, less pain, less free nerve endings
  • Lateral portion of the plantar surface of the foot: <1 year old
• Skin puncture specimen


  Compared to venous specimen: lower WBCs, hemoglobin, hematocrit, RBCs, platelets
• Venipuncture sites


  • Median cubital = preferred, most stable
  • Cephalic (lateral)
  • Basilic (medial)
• Common needle gauges


  • 19, 20, 21
  • Routine: 20g
• Common needle lengths


  • 1-1.5 inches
• Color coded needle hubs (gauge)

  • 18 = pink
  • 21 = green
  • 22 = gray
  • 23 = blue/light blue/turquoise
• Venipuncture angle


  15 degrees
• Blood bank angle


  45 degrees, 10-20 degrees once in the skin
• Tourniquet


  1. 4 inches above the site (7.5-10cm), not exceed 1min/2mins, prolonged application causes hemoconcentration
• BP cuff as tourniquet

  40-60 mmHg
• Crying


  Increases cell count
• Lying down


  Causes hemodilution, decreases PCV by 8%, decreases WBC
• Lying up


  Causes hemoconcentration
• IV line


  Collect on the other arm, if both arms: stop IV for 2mins, collect blood below the IV line, appropriate for all analytes except glucose and phosphorus
• Hematopoiesis


  Cellular formation, proliferation, differentiation and maturation of blood cells
• Embryonic hemoglobins


  • Gower 1 = Zeta2 + Epsilon2
  • Portland = Zeta2 + Gamma2
  • Gower 2 = Alpha2 + Epsilon2
• Fetal hemoglobins


  • HbF = Alpha2 + Gamma2
  • HbA1 = Alpha2 + Beta2
  • HbA2 = Alpha2 + Delta2
• In adults, HbA1 is ≥95%, HbA2 is 1.5-3%, and HbF is <2%
• In neonates, HbF is 60-80% and HbA is 20-40%
• Marrow specimens


  • Trephine (Core) Biopsy
  • Aspiration
• Posterior iliac crest is the safest site for bone marrow aspiration/biopsy
• 1. E ratio


  Numeric expression comparing the relative number of granulocytic precursors with the relative erythroid precursors in the bone marrow, normal value is 2:1 to 4:1 (average 3:1)
• Precursors included in M:E ratio


  • Neutrophilic, Eosinophilic, Basophilic precursors = Myeloid
  • Erythroid precursors
• Bone marrow cellularity


  Percentage of marrow space occupied by hematopoietic cells compared with fat, normocellular marrow (adult) has 10-50% fat and 40-60% (average 50%) hematopoietic elements