Clinical Pathology Basics
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Questions and Answers

What is the main focus of clinical pathology?

  • The research of animal anatomy
  • The management of veterinary practices
  • The use of laboratory methods for diagnosis and treatment of disease (correct)
  • The surgical treatment of diseases

    • Why is it important to analyze blood samples quickly?

  • To ensure the blood remains sterile
  • To prevent the effects of anticoagulants from interfering (correct)
  • To obtain insurance claims faster
  • To preserve the natural color of the plasma

    • Which anticoagulant is preferred for routine hematologic tests like CBC assays?

  • EDTA (correct)
  • Calcium chloride
  • Heparin
  • Sodium citrate

    • What role does citrate play in blood sample analysis?

    <p>It forms an ionic bond with Ca2+ to enable coagulation</p> Signup and view all the answers

    What two diagnostic procedures are crucial in selecting the appropriate tests?

    <p>Obtain a complete history and perform a physical examination</p> Signup and view all the answers

    How does citrate aid in coagulation testing?

    <p>By allowing coagulation enzymes to function in citrated plasma</p> Signup and view all the answers

    In which situation is plasma sample analysis rarely done?

    <p>Within hours after collection</p> Signup and view all the answers

    What is a common misconception about physical examinations in clinical pathology?

    <p>They are unnecessary if a history is obtained</p> Signup and view all the answers

    What is the main reason for quickly processing whole blood samples?

    <p>Cells die within a few hours.</p> Signup and view all the answers

    What happens if samples are centrifuged before the retraction of the clot?

    <p>Serum gets trapped in the soft fibrin clot.</p> Signup and view all the answers

    Which component is absent in serum that is present in plasma?

    <p>Fibrinogen</p> Signup and view all the answers

    Why should fluid samples be shipped on cool packs?

    <p>To preserve the integrity of the samples.</p> Signup and view all the answers

    What is a recommended practice to protect serum tubes during shipping?

    <p>Wrap them in bubble wrap.</p> Signup and view all the answers

    What should not be done when shipping formalin containers?

    <p>Pack them with serum tubes.</p> Signup and view all the answers

    Which statement about the composition of serum is true?

    <p>Serum is missing coagulation factors like fibrinogen.</p> Signup and view all the answers

    When should centrifugation of blood samples be started for optimal results?

    <p>After the retraction of the clot.</p> Signup and view all the answers

    What is the primary reason citrate is preferred for the collection of whole blood?

    <p>It has low toxicity.</p> Signup and view all the answers

    What is the effect of oxalate on blood samples?

    <p>It distorts morphologic features of cells.</p> Signup and view all the answers

    Why must a laboratory be contacted before sample collection?

    <p>To obtain specific test instructions.</p> Signup and view all the answers

    What is the major drawback of using heparin as an anticoagulant?

    <p>It allows clotting to occur over time.</p> Signup and view all the answers

    Which of the following is necessary for obtaining useful results for an analyte?

    <p>Proper sample collection and processing.</p> Signup and view all the answers

    What type of samples are frequently used for clinical laboratory assays?

    <p>Blood and its major components.</p> Signup and view all the answers

    What is the role of an analyte in clinical laboratory tests?

    <p>It is the substance or cell of interest.</p> Signup and view all the answers

    Which of the following is a disadvantage of using oxalate as an anticoagulant?

    <p>It alters morphologic features of leukocytes.</p> Signup and view all the answers

    What color is normal plasma in dogs and cats?

    <p>Colorless to light</p> Signup and view all the answers

    What does a pink to red plasma color indicate?

    <p>Hemoglobinemic plasma</p> Signup and view all the answers

    Which component can be visualized as a white layer between the RBCs and plasma?

    <p>Buffy coat</p> Signup and view all the answers

    How is hematocrit determined?

    <p>By centrifugation of blood</p> Signup and view all the answers

    What does the packed cell volume (PCV) indicate?

    <p>The percentage of blood composed of erythrocytes</p> Signup and view all the answers

    What is the function of reticulocyte counts?

    <p>To estimate white blood cell counts</p> Signup and view all the answers

    Which plasma condition is characterized as whitish to pink and opaque?

    <p>Lipemic plasma</p> Signup and view all the answers

    What is an indication of the oxygen transport capacity of blood?

    <p>Packed cell volume (PCV)</p> Signup and view all the answers

    What is the main reason for the longer packing time of ruminant red blood cells compared to those of dogs, cats, and horses?

    <p>Ruminant RBCs take longer to settle.</p> Signup and view all the answers

    How long should microhematocrit tubes be spun for ruminants?

    <p>10 minutes</p> Signup and view all the answers

    Which method yields more accurate RBC counts when standardized for mammalian blood?

    <p>Using automated counters</p> Signup and view all the answers

    What is the formula to calculate Mean Corpuscular Volume (MCV)?

    <p>MCV = (Hematocrit x 10) / RBC count in millions</p> Signup and view all the answers

    What happens to MCV in macrocytic anemias such as those caused by B12 or folic acid deficiencies?

    <p>MCV increases</p> Signup and view all the answers

    Why are hemocytometer-derived RBC counts considered of limited value?

    <p>They have a large degree of error.</p> Signup and view all the answers

    What is a primary concern when using automated counters for avian blood?

    <p>Counting nucleated RBCs and WBCs together</p> Signup and view all the answers

    What effect does reticulocytosis have on the MCV value?

    <p>It causes an increase in MCV.</p> Signup and view all the answers

    Study Notes

    Clinical Pathology

    • A sub-specialty of pathology using laboratory methods for disease diagnosis and treatment.
    • Focuses on studying disease in clinical settings using laboratory assays.
    • Requires obtaining a complete history and performing a complete physical examination for accurate diagnosis

    Samples for Laboratory Assays

    • Analyte: Substance or cell being detected or quantified in blood samples.
    • Blood: Most common sample used for laboratory assays, but must be collected and processed properly.
    • Whole blood: Must be mixed with an anticoagulant to prevent clotting and maintain cells in suspension. Analyze quickly (within minutes or hours) due to cell death.
    • Plasma: Fluid component of anticoagulated blood after centrifugation. Contains anticoagulants that can interfere with some assays.
      • EDTA: Preferred for most hematologic tests, including CBC.
      • Citrate: Preferred for coagulation system tests.
      • Oxalates: Used for glucose and lactate assays but not suitable for hematologic samples.
      • Heparin: Used for special assays like blood gas analysis and some clinical chemistry assays.

    Serum

    • Fluid component of coagulated blood after centrifugation.
    • Serum: Contains the same components as plasma but lacks fibrinogen (a major coagulation protein).
    • Centrifugation should be performed after clot retraction (at least 30 minutes) to avoid trapping serum in the fibrin clot.

    Shipping Samples

    • Protect samples from breakage, temperature extremes, and exposure to formalin.
    • Use sturdy containers and bubble wrap for protection during transportation.
    • Wrap samples with paper towels, avoid direct contact with ice packs to prevent freezing and cell lysis.
    • Label all tubes and slides with patient identification and contents.

    Erythrogram

    • Comprises:
      • Red blood cell (RBC) counts.
      • RBC mass (hematocrit).
      • Hemoglobin concentration.
      • RBC indices (cell size, hemoglobin content).
      • Reticulocyte counts.
      • Nucleated RBC count.
      • RBC morphologic features.
      • Parasite screening.

    Packed Cell Volume (PCV)

    • Percentage of blood composed of erythrocytes.
    • Determined by centrifugation, separating red blood cells from plasma and leukocytes.
    • RBC packing time varies by species.
      • Ruminants require 10 minutes.
      • Other species 3 minutes.

    Hemoglobin Determination

    • Most accurate indicator of blood's oxygen transport capacity.
    • Approximately 1/3 of the PCV when erythrocytes are normal size.
    • Methods: Acid-hematin method, microhematocrit, Tallqvist Hgb scale, Dare chemoglobinometer, Cyanmethemoglobin method.

    RBC Counts

    • Hemocytometer-derived counts have a high degree of error and limited value, except for avian species.
    • Automated counters provide more accurate counts for mammalian blood.
    • Validation for avian blood is less reliable, as all nucleated cells are counted, including RBCs, WBCs, and thrombocytes.
    • RBC count enables determination of MCV and MCH.

    Mean Corpuscular Values (MCV)

    • MCV: Measures the average volume of individual RBCs (femtoliters - fl).
    • Calculation: MCV = (Hematocrit x 10)/ RBC count (in millions).
    • MCV (↑): Indicates macrocytic anemia, often caused by B12 or folic acid deficiencies.
    • MCV (↓): Indicates iron deficiency anemia.
    • Increase in MCV: Can also be caused by reticulocytes.

    Plasma Color and Transparency

    • Normal plasma can be clear and colorless (dogs and cats) to light (horses and cows).
    • Icteric: Yellow and clear.
    • Hemoglobinemic: Pink to red and clear.
    • Lipemic: Whitish to pink and opaque.

    Buffy Coat

    • A white layer between the RBCs and plasma, mainly composed of leukocytes and platelets.
    • Buffy coat width can be used to estimate white blood cell counts.
    • Plasma above the buffy coat can be examined microscopically to detect microfilaria.

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    Description

    This quiz covers the essential concepts of clinical pathology, focusing on laboratory methods used for disease diagnosis and treatment. You'll explore the types of samples utilized in laboratory assays and the importance of proper sample handling for accurate results. Test your knowledge on analytes, blood samples, and their significance in clinical settings.

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