Platelet Count Quiz
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Questions and Answers

What mechanism allows the pipette to fill automatically with blood?

Capillary action.

How is excess blood removed from the pipette after filling?

By squeezing the reservoir to apply negative pressure.

What formula is used to calculate platelet count?

Platelet count = # of Cells x 10 x 200/4.

What is the reference range for a normal platelet count?

<p>150,000 – 400,000.</p> Signup and view all the answers

Why is it necessary to cover the overflow chamber of the pipette during the procedure?

<p>To prevent air from entering which could interfere with accurate measurement.</p> Signup and view all the answers

What does an elevated Mean Platelet Volume (MPV) suggest about platelet size and bone marrow activity?

<p>Elevated MPV suggests larger platelets, which may indicate active bone marrow regeneration.</p> Signup and view all the answers

How does accurate platelet counting impact the management of thrombocytopenia?

<p>Accurate platelet counting is crucial for diagnosing and managing thrombocytopenia effectively.</p> Signup and view all the answers

What is the primary use of a hemocytometer in clinical settings?

<p>A hemocytometer is primarily used for accurate estimation of cell concentration in blood samples.</p> Signup and view all the answers

What conditions are associated with platelet overactivation?

<p>Platelet overactivation is linked to conditions such as deep vein thrombosis and heart attacks.</p> Signup and view all the answers

In what microbiological applications is a hemocytometer utilized?

<p>A hemocytometer is used to quantify microbial populations in cultures like bacteria, yeast, or fungi.</p> Signup and view all the answers

Why is it important to understand the implications of platelet disorders?

<p>Understanding platelet disorders is vital as they contribute to various hematologic and vascular diseases.</p> Signup and view all the answers

What role does an automated analyzer play in platelet counting?

<p>An automated analyzer provides more accurate platelet counts and generates MPV measurements.</p> Signup and view all the answers

What are the potential consequences of mismanagement in thrombocytosis?

<p>Mismanagement in thrombocytosis can lead to complications such as strokes and peripheral artery disease.</p> Signup and view all the answers

What are the main advantages of manual platelet counting over automated methods, particularly in resource-limited settings?

<p>Manual platelet counting is cheaper, uses a standard dilution factor for reproducibility, and minimizes sample handling errors.</p> Signup and view all the answers

Explain how operator skill affects the accuracy of manual platelet counting.

<p>Accuracy relies heavily on the operator's skill and experience, as improper loading or uneven mixing can yield inaccurate counts.</p> Signup and view all the answers

Identify a clinical situation where manual platelet counting serves as a backup or verification method.

<p>Manual platelet counting can verify automated platelet counts in diagnosing thrombocytopenia or thrombocytosis.</p> Signup and view all the answers

Discuss the significance of hypogranular platelets and the conditions they may suggest.

<p>Hypogranular platelets, which contain less than 20 granules, may indicate myelodysplastic syndromes and other disorders.</p> Signup and view all the answers

How does manual platelet counting facilitate hematological studies despite the prevalence of automation?

<p>It allows for detailed evaluation of platelet function and morphology, fundamental in hematology research.</p> Signup and view all the answers

What is the significance of the fixed distance the coverslip is held from the grid in a hemocytometer?

<p>It ensures precise volume measurements.</p> Signup and view all the answers

Describe the grid structure of the central square in the hemocytometer.

<p>The central square is divided into 25 medium squares, which are further subdivided into 16 smaller squares for a total of 400 squares.</p> Signup and view all the answers

What is the purpose of diluting the sample when preparing to use a hemocytometer?

<p>Dilution ensures that the cell concentration falls within the measurable range.</p> Signup and view all the answers

How does the design of the coverslip enhance the function of the hemocytometer?

<p>The coverslip is designed to fit precisely, maintaining a fixed distance and aiding accurate volume measurement.</p> Signup and view all the answers

What specific rules must be followed when counting cells in a hemocytometer to avoid double-counting?

<p>Only count cells touching specific borders of the chosen squares.</p> Signup and view all the answers

What types of cells are counted in the central square versus the four corner squares of a hemocytometer?

<p>The central square is used for counting red blood cells, while the four corner squares are used for counting larger cells like white blood cells.</p> Signup and view all the answers

Why is thorough mixing of the sample essential before loading it onto the hemocytometer?

<p>Thorough mixing ensures even distribution of the cells within the sample.</p> Signup and view all the answers

What is the dimension of each medium square in the central square of a hemocytometer?

<p>Each medium square measures 1 mm x 1 mm.</p> Signup and view all the answers

What is the significance of allowing the blood to mix with the diluent in platelet analysis?

<p>It ensures adequate mixing for accurate platelet counting.</p> Signup and view all the answers

List two potential causes of thrombocytopenia.

<p>Bone marrow failure and immune thrombocytopenic purpura (ITP).</p> Signup and view all the answers

How is the platelet count calculated from the hemocytometer readings?

<p>Platelet count = # of Cells x 1 x 10 x 100.</p> Signup and view all the answers

What can abnormal platelet morphology indicate?

<p>It may indicate macrothrombocytes or a rare bleeding disorder.</p> Signup and view all the answers

What are the potential risks associated with thrombocytosis?

<p>Increased risk of clot formation leading to heart attacks or strokes.</p> Signup and view all the answers

Why is it necessary to let the mixture stand for 10 minutes before counting platelets?

<p>To ensure complete interaction between the blood sample and the diluent.</p> Signup and view all the answers

What steps should be taken after charging the hemocytometer and before mounting it on the microscope?

<p>Discard several drops (3-4) and place the hemocytometer in a moist petri dish for 10 minutes.</p> Signup and view all the answers

What might easy bruising and prolonged bleeding signify in a patient?

<p>These symptoms can indicate thrombocytopenia or platelet dysfunction.</p> Signup and view all the answers

What advantages does the manual method of direct platelet counting offer in laboratories without automated platelet counters?

<p>It allows observation of platelet morphology alongside counting and provides accurate results when automated methods are unavailable.</p> Signup and view all the answers

Identify two potential limitations of the manual direct platelet counting method.

<p>Subject to human error and requires meticulous sample preparation.</p> Signup and view all the answers

What is the purpose of the Reese and Ecker fluid in the platelet counting procedure?

<p>It is used for diluting the blood sample to facilitate counting under a microscope.</p> Signup and view all the answers

Describe the role of the hemocytometer in the counting process.

<p>The hemocytometer serves as a counting chamber where the diluted blood sample is analyzed under a microscope.</p> Signup and view all the answers

List the components included in the Unopette system for direct platelet counting.

<p>Capillary pipette, diluent reservoir, protective sleeve, and mixing device.</p> Signup and view all the answers

Why might it be difficult to accurately count platelets in cases of severe thrombocytopenia?

<p>Platelet numbers are extremely low, making it challenging to obtain a reliable count.</p> Signup and view all the answers

What steps must be taken to prepare the hemocytometer for counting?

<p>Place it over the moistened filter paper inside the petri dish and allow it to stand for 5 minutes.</p> Signup and view all the answers

Explain the importance of wiping off blood on the pipette tip during sample preparation.

<p>Wiping prevents contamination and ensures an accurate volume of blood is used for dilution.</p> Signup and view all the answers

How does the mixing device in the Unopette system contribute to the platelet counting process?

<p>It ensures thorough mixing of the blood with the diluent, which is critical for accurate results.</p> Signup and view all the answers

What factors can interfere with the accuracy of manual platelet counts?

<p>Platelet clumps or debris can obstruct visibility and lead to erroneous results.</p> Signup and view all the answers

Flashcards

Hemocytometer

A specialized slide with a grid used for counting cells in a sample.

Coverslip

A thin piece of glass placed on the hemocytometer to create a precise volume for cell counting.

Central Square

The largest square in a hemocytometer's grid, divided into 25 medium squares, and used for counting red blood cells (RBCs).

Corner Squares

Four squares on the hemocytometer's grid used for counting larger cells like white blood cells (WBCs).

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Sample Dilution

The process of adjusting the concentration of the sample to ensure accurate cell counting in the hemocytometer.

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Sample Mixing

Thoroughly mixing the sample before loading into the hemocytometer to ensure even distribution of cells.

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Loading the Sample

Introducing the prepared sample into the hemocytometer chamber, using a pipette to fill in the grooves.

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Counting Rules

Specific guidelines followed to avoid double-counting cells during the microscopic observation of the hemocytometer grid.

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Mean Platelet Volume (MPV)

The average size of platelets in a blood sample.

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Elevated MPV

Indicates larger platelets, often suggesting bone marrow regeneration (making new blood cells).

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Thrombocytopenia

A condition with low platelet count, increasing risk of bleeding.

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Thrombocytosis

A condition with a high platelet count, increasing risk of blood clots.

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Platelets and Deep Vein Thrombosis (DVT)

Overactive platelets can contribute to DVT (blood clot in a deep vein, often in the leg) by increasing clotting tendency.

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Platelets and Pulmonary Embolism (PE)

Overactive platelets can contribute to PE (blood clot traveling to the lungs) by increasing clotting tendency.

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Platelet Disorders and Vascular Diseases

Disorders affecting platelets can contribute to a variety of vascular diseases affecting blood vessels.

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Direct Platelet Count

A manual method used to count platelets in blood samples, usually employed when automated methods are unavailable.

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Reese and Ecker Fluid

A specific diluting fluid used in manual platelet counts, designed to preserve platelet integrity and facilitate counting.

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Unopette System

A self-contained system designed for manual blood cell counting, simplifying dilution and counting processes.

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Capillary Pipette

A small, thin glass tube used to draw and transfer small volumes of blood for analysis.

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Diluent Reservoir

A container within the Unopette system holding the diluting fluid.

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Manual Platelet Counting

The process of directly counting platelets under a microscope using a hemocytometer and diluting fluid.

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Platelet Morphology

The shape and structure of platelets observed under a microscope.

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Limitations of Direct Platelet Count

Challenges associated with manual platelet counting, including human error, variability, difficulty in counting low numbers, and interference from debris.

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Capillary Action

The phenomenon where a liquid rises in a narrow tube due to the cohesive forces between liquid molecules and adhesive forces between the liquid and the tube's surface.

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Platelet Count Formula

The formula used to calculate platelet count in a blood sample: Platelet count = (# of Cells x 10 x 200) / 4

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Reference Range

The normal range for the platelet count in a healthy individual, typically between 150,000 and 400,000 platelets per microliter of blood.

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Negative Pressure

The force created by removing air from a chamber, like squeezing a reservoir to create a vacuum.

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Overflow Chamber

The section of a pipette that is designed to collect excess blood and prevent it from entering the counting chamber.

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Why is Manual Platelet Counting Done?

It is done to diagnose thrombocytopenia or thrombocytosis, verify automated counts, or study platelet function and morphology.

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What are the Benefits of Manual Platelet Counting?

It provides precise counts when done correctly, uses a standard dilution for reproducibility, is cheaper, and has a pre-filled diluent reservoir.

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What are the Limitations of Manual Platelet Counting?

It takes longer than automated counting, requires skilled operators, and may not detect very low platelet counts accurately.

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What are Hypogranular Platelets?

Platelets with a rim of cytoplasm that contains less than 20 granules.

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What is Thrombocytopenia?

A condition characterized by a low platelet count in the blood.

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What are the causes of Thrombocytopenia?

Causes include bone marrow failure, immune thrombocytopenic purpura (ITP), infections, or certain medications.

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What are the symptoms of Thrombocytopenia?

Symptoms include easy bruising, prolonged bleeding, petechiae, and potential internal hemorrhaging.

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What is Thrombocytosis?

A condition characterized by an abnormally high platelet count in the blood.

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What are the causes of Thrombocytosis?

Causes include inflammation, infections, iron deficiency, or myeloproliferative disorders such as essential thrombocythemia.

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What are the risks of Thrombocytosis?

Increased risk of blood clots (thrombosis), which can lead to serious conditions like heart attacks, strokes, or pulmonary embolisms.

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What is Macrothrombocytosis?

A rare bleeding disorder characterized by abnormally large platelets and a low platelet count.

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What is the importance of Platelet Morphology Assessment?

Abnormal platelet morphology (size and shape) can indicate underlying conditions like Macrothrombocytosis.

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Study Notes

Platelet Count (Direct)

  • Platelets maintain blood vessel integrity, initiate repairs, adhere to damaged vessels, and aggregate.
  • Secrete proteins and small molecules for clot formation (thrombosis).
  • Crucial for hemostasis (wound sealing, vessel repair).
  • Platelets are small, round or oval, anucleate, and granular.
  • Formed from megakaryocytes in the bone marrow.
  • 2-4 µm in diameter.

High Platelet Counts (Thrombocytosis)

  • High platelet counts may indicate inflammation or trauma, the body increasing platelet production for healing.
  • Essential thrombocythemia: a rare malignant condition with extremely high platelets and uncontrolled production.

Low Platelet Counts (Thrombocytopenia)

  • Often caused by medications.
  • Leads to easy bruising, uncontrolled bleeding, and risk of hemorrhaging.
  • Disrupts hemostasis, increasing the risk of bleeding.

Counting and Analysis

  • Platelets are counted visually using a hemocytometer or automated analyzers.
  • Automated analyzers provide more accurate counts and calculate Mean Platelet Volume (MPV).
  • Elevated MPV suggests larger platelets; potentially indicating bone marrow regeneration.

Significance

  • Accurate platelet counts are essential for diagnosing conditions like thrombocytopenia and thrombocytosis.
  • Platelet disorders contribute to various hematologic and vascular diseases.

Conditions Associated with Platelets

  • Deep vein thrombosis (DVT)
  • Pulmonary emboli
  • Heart attacks
  • Strokes
  • Peripheral artery disease
  • Recurrent miscarriages
  • Overactivation can disrupt pregnancy.

Hemocytometer

  • Specialized chamber for blood cell counting.
  • Used to calculate cell concentrations in samples.
  • Useful when automated counters are unavailable or impractical.

Hemocytometer Structure

  • Thick glass slide with a rectangular indentation forming a chamber.
  • Grid etched on the surface.

Procedures in Using a Hemocytometer

  • Prepare the sample: dilute if necessary to ensure measurable cell concentrations and proper mixing.
  • Load the sample into the chamber, evenly distributing the solution without overfilling.
  • Use a microscope to count cells within designated squares.
  • The procedures include rules for inclusion and exclusion.
  • Exclude cells that touch the bottom or right edges of the square.
  • Include cells touching top and left edges of the square.
  • Calculate results according to the formula provided.

Materials and Equipment Used

  • Pipettes for diluting samples.
  • Microscopes for visualization.
  • Diluting fluids.
  • Hemocytometer.
  • Coverslips (appropriate thickness).

Direct Platelet Count (Reese and Ecker Method)

  • Manual technique used to count platelets.
  • Used with a hemocytometer.
  • Dilutes the whole blood and stains platelets.
  • Manual counting on a defined volume in the chamber.
  • Calculates the platelets per microliter of blood.

Direct Platelet Count (Unopette System)

  • Self-contained unit includes capillary pipette, diluent reservoir, protective sleeve, and mixing device.
  • Simplifies the process of diluting and counting blood cells, accurately providing results.

Platelet Morphology Assessment

  • Abnormal platelet morphology may indicate:
    • Macrothrombocytes (giant platelets).
    • Hypogranular platelets (reduced granules).
  • These can suggest conditions such as myeloproliferative disorders or other inherited conditions.

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Description

Test your knowledge on platelet counts, their role in hemostasis, and conditions related to abnormal platelet levels. This quiz covers aspects of thrombocytosis and thrombocytopenia, including causes and implications of high and low platelet counts.

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