WBC Count

Hemocytometer Overview

  • A hemocytometer is a specialized counting device used for counting blood cells.

  • Key features include:

    • Thick sides, with a counting chamber in the middle.

    • Special coverslips that are longer and thicker than standard coverslips, and reusable after cleaning.

  • Etymology: The term "hemocytometer" combines "hemo" (blood) and "cytometer" (measurer of cells).

Counting Procedure with Hemocytometer

  • Preparation:

    • Traditionally, blood samples were lysed using specific methods (e.g., UniPet system) for cell counting.

    • The new method involves using a Lumatec system that uses smaller volumes of liquid with a dye to enhance visibility of white blood cells.

  • Blood Sample Collection:

    • Use short capillary tubes filled with whole blood from lavender top tubes.

    • Clean the exterior of the tubes to avoid contamination of the sample volume.

Utilizing the Hemocytometer

  • After preparing the blood sample:

    • Invert the tube to mix, wait approximately 30 seconds before processing.

  • The hemocytometer has raised areas covered by the coverslip, creating a precise counting area (grids).

  • Grid Structure:

    • The counting area features 9 large squares, subdivided into smaller squares.

    • Only the 4 large corner squares will be counted for white blood cell calculations.

Cell Counting Process

  • Focus the microscope using:

    • Start with a 4x objective to locate the grid.

    • Switch to a 10x objective for counting.

  • Utilize a clicker counter to keep track of cell counts, ensuring it resets to zero between counts on sides of the hemocytometer.

  • Perform counts on both sides, ensuring accuracy through a consistency check:

    • Counts on both sides should be within a 10% range to validate the results.

Calculating White Blood Cell Count

  • If counts are consistent:

    • Average the two counts recorded from each side of the hemocytometer.

  • Final Calculation:

    • Multiply the averaged count by 50 to determine the quantity of white blood cells per microliter.

    • Example: Average count of 92 would yield 4,600 white blood cells per microliter.

Tips for Accurate Counting

  • Ensure proper illumination of the microscope:

    • Use the iris diaphragm to control light intensity; avoid excessive brightness which can obscure visibility.

  • Count cells, record the data, average the results, and perform the final multiplication to get the cell count.

Summary of Benefits from New Method

  • The updated method using Lumatec allows for:

    • Easier visibility of cells due to staining.

    • Faster and more accurate blood analysis with reduced liquid volume and quicker preparation.