Complete Blood Count

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Complete Blood Count
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Hematology

• Hematology testing represents an important role
  of the veterinary technician to provide accurate
  and reliable clinical laboratory test results to
  the veterinarian
• A complete hematology profile is indicated for
  diagnostic evaluation of disease state, well
  animal screening, (e.g. geriatric) and screening
  tool before surgery

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CBC Include

• White and red blood cell counts
• Hemoglobin concentrations
• Packed cell volume (PCV)
• Differential white blood film examination
• Calculation of absolute values/erythrocyte
  indices

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Types of Cellular Elements

• Red blood cells Erythrocytes
• White blood cells Leukocytes
• Neutrophils
• Eosinophils
• Basophils
• Lymphocytes
• Monocytes
• Platelets Thrombocytes (not true cells)

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CBC

• Total RBC count
• PCV
• Plasma protein concentration (TP)
• Total WBC
• Blood film examination differential WBC count,
  erythrocyte and leukocyte morphology, platelets
  estimation.
• Reticulocyte count when the patient is anemic
• Hemoglobin concentration
• Erythrocyte indices

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Quality control

• Automated analyzers can provide accurate and
  cost-effective results. However, care should be
  taken in choosing the most appropriate instrument
  a clinic
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Cell counts

• Counting of erythrocytes and leukocytes is a
  routine part of the CBC. Cells counts can be
  performed by manual and automated methods.
• The total WBC (leukocyte) count is one of the
  most useful values determined in a CBC
• Total RBC (erythrocyte) and platelet
  (thrombocyte) counts, although are more difficult
  and less accurate, may also be performed
  manually with a hemocytometer or by automated
  methods

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Hemocytometer - Unopette

• The Unopette system is a standardized method
  for enumerating leukocytes using fresh whole
  blood via a capillary puncture. This system is
  made up of the following components

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• 1    A reservoir that contains a premeasured
  volume (1.98mL) of a 3 glacial acetic acid
  solution.
• 2 Self-filling, color coded 20 µL pipet.
  This pipet is constructed with one end that fits
  into the reservoir. This end is designated as the
  overflow chamber.
• 3    Pipet shield that covers and protects the
  pipet. The end of the shield is pointed for the
  purpose of puncturing the reservoir diaphragm
  before use.
• 4     See Figure 1 for an illustration of the
  Unopette system

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• The Hemacytometer has counting chambers used to
  determinate the number of cells per microliter
  (µl, sometimes referred to as cubic centimeters)
  of blood.
• Several models are available, but the most common
  type used has two identical sets of fine grids of
  parallel and perpendicular etched lines called
  Neubauer rulings

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Neubaur system
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related
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Hematocrit - PCV

• In the CBC, we determine the number of RBCs in
  several different ways. The quickest and easiest
  is called the hematocrit, also referred to as the
  packed cell volume (PCV)
• PCV / 6 est RBC count / µL

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Plasma Protein Concentration

• Plasma Protein (TP) concentrations estimation by
  refractometry is an important component of the
  CBC in all species
• The plasma used to determinate the PCV is
  collected by breaking the hematocrit tube just
  above the Buffy coat- plasma interface

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Hemoglobin (Hgb)

• Hemoglobin counts are usually done with an
  automated analyzer. The analyzer will mix a
  small amount blood with a solution to lyse the
  cells. It will then compare the color of the
  lysed cells to the normal

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Hematology values
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Erythrocyte Indices

• Determination of erythrocyte indices is helpful
  in the classification of certain types of anemia
• The erythrocyte indices include the mean
  corpuscular volume (MCV), mean corpuscular
  hemoglobin (MCH) and MCH concentration mean
  corpuscular hemoglobin concentration (MCHC).
• The indices can provide an objective measure of
  the size of the RBCs and their average hemoglobin
  concentartion.

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Mean corpuscular volume (MCV)

• The MCV expresses the average volume (or size) of
  the individual erythrocyte. Using the total
  erythrocyte count, hemoglobin content and packed
  cell volume, it is possible to calculate the
  volume of an average erythrocyte and its
  hemoglobin concentration. Dividing the packed
  cell volume by the RBC concentration and
  multiplying by 10 determines the MCV.

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Mean corpuscular hemoglobin concentration (MCHC)

• The MCHC is the concentration of hemoglobin in
  the average erythrocyte, or the ratio of weight
  of hemoglobin to the volume in which it is
  contained.
• The MCHC is calculated by dividing the hemoglobin
  concentration by the PCV () and multiplying by
  100.

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Mean corpuscular hemoglobin (MCH)

• MCH is the weight of hemoglobin contained in the
  average erythrocyte. The MCH is calculated by
  dividing the hemoglobin concentration by the RBC
  concentration and multiplying by 10.

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Blood films

• Remember ! The blood film is used to perform the
  differential WBC count estimate platelet
  numbers and evaluate the morphological features
  of WBCs, RBCs and platelets.

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Performing the Differential Cell Count

• This is where the different white blood cells are
  tallied separately. This can be done by a blood
  counting machine, or by hand.
• To manually count the different cells, first you
  must make a perfect slide. Stain the slide once
  it is dry.
• Using a cell counter you will tally a total of
  100 cells (this will make it easy to turn the
  numbers into a )

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• The percentages will aid in initial diagnoses,
  interpretation should be based on the absolute
  numbers of the various cells.
• Absolute numbers are obtained by multiplying the
  percentage by the total leukocyte count

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• Because 100 WBC are counted , the number of each
  WBC type observed is recorded as a percentage.
• This is called the relative WBC count
• Various counting devices are available to help
  perform the differential WBC
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