University:
University of Cambridge
Course:
MBBS | Bachelor of Medicine Bachelor of Surgery
Academic year:

2024
Views:

382

Pages:

4
Author:

Mysan Cabanes

MANUAL CELL COUNT FOR RED BLOOD CELLS AND WHITE BLOOD CELLS HEMOCYTOMETER ● The most commonly used is the ____________ with improved Neubauer ruling ● It is composed of 3mm x 3mm square counting or grid (total area _________), separated by an H-shaped moat ● The distance between each counting surface and the coverslip is 0.1mm ● The total volume of one entire grid or counting area on one side of the hemocytometer is 0.9 mm3 ● Each of the four corner (WBC) squares is subdivided further into 16 squares, and the center square subdivided into 25 smaller squares. Each of these smallest squares is 0.2 mm x 0.2 mm which is 1/25 of the center square or 0.04 mm2 General formula/ calculation for cell counting in Neubauer counting chamber: A. Cell counted x Area correction factor x dilution factor X Dilution (1/200) B. Total cells counted x Dilution Total area counted (mm2) x Depth (0.1) ● The difference between the total cells counted on each side should be ______. A greater variation could indicate an uneven distribution, which requires the procedure to be repeated MANUAL CELL COUNTS WITH MOST COMMON DILUTIONS AND COUNTING AREA OTHER CELL COUNTING CHAMBERS: ● Burker-Turk ● Fuchs-Rosenthal ● Jessen ● Petroff-Hausser ● Malassez ● Sedgwick-Rafter MANUAL RBC COUNT: Reference values: Male: Female: At birth: RBC Diluting Fluids: ● Dacie’s (Formol Citrate) ● Hayem’s fluid ● Gower’s fluid ● Toisson’s fluid ● Bethell’s fluid ● Normal saline solution ● 3.8% sodium citrate Procedure: 1. Do patient identification. 2. Obtain 2ml EDTA whole blood. 3. Aspirate blood in the RBC thoma pipette up to the 0.1 or 0.2 mark. 4. Deliver diluting fluid up to the 101 mark. 5. Properly mix the blood and the diluting fluid for 5 minutes (manually or with the aid of a pipette mixer). 6. Discard 3-4 drops of the solution and correctly charge the hemocytometer counting chamber. 7. Count the RBCs in the 4 corner intermediate squares and 1 central intermediate square with 16 small squares of the central large square. 8. Compute and record the results in the performance sheet. Moist chamber: moist chamber may be made by placing a piece of damp filter paper in the bottom of a Petri dish. An applicator stick broken in half can serve as a support for the hemacytometer. MANUAL WBC COUNT: Reference Values: Adult: At birth: WBC Diluting Fluids: ● 1-3% Acetic acid ● 1% HCL ● 1% Ammonium oxalate ● Turk’s Diluting acid NOTE: The diluting fluid lyses the non-nucleated RBCs in the specimen to prevent their interference in the count. The typical dilution of blood for the WBC count is 1:20. A hemocytometer is charged (filled) with the well-mixed dilution and placed under a microscope and the number of cells in the four large corner squares (4 mm2) is counted. PROCEDURE: Procedure: 1. Do patient identification. 2. Obtain 2ml EDTA whole blood. 3. Aspirate blood in the WBC thoma pipette up to the 0.5 mark. 4. Deliver diluting fluid up to the 11 mark. 5. Properly mix the blood and the diluting fluid for 5 minutes (manually or with the aid of a pipette mixer). 6. Discard 3-4 drops of the solution and correctly charge the hemocytometer counting chamber. 7. Count the WBCs in the 4 corner large squares with 16 intermediate squares. 8. Compute and record the results in the performance sheet. PRACTICE QUESTIONS:

Manual Cell Count For Red Blood Cells and White Blood Cells

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