Total Red Blood Cell Count

The total red blood cell count is the number of erythrocytes per cubic millimeter of blood. A range of 4.2 million to 6.0 million per cubic millimeter of blood is considered to be normal for a male. A range of 3*8 million to 5.4 million per cubic millimeter of blood is considered to be normal for a female.

Exercise 26.2

Materials: (Figure 26.1) Cotton ball soaked in alcohol Dry cotton ball Sterile disposable lancet Unopette for red blood cell counts Hemacytometer and cover glass Mechanical hand counter Microscope

1. Obtain a Unopette for red blood cell counts. It consists of three parts: reservoir\ pipette, and shield. The shield is used to introduce a hole into the reservoir. Puncture the reservoir with the shield before proceeding any further. The reservoir; which has red writing on the bottom and is larger than the reservoir for white blood cell counts, contains a saline solution which will dilute the red blood cells. The pipette, which has the number "10" etched in pink, is used to draw bloodfrom the finger.

2. Scrub a finger with alcohol. Stick the finger with a sterile lancet. Immediately after using the lancet, place it in the bio-hazard container. Do not recap the lancet Any disposable object contaminated with blood should be placed into the bio-hazard container

3. Place the pipette into the blood at an angle slightly above horizontal Capillary action will draw the blood into the pipette. The blood will only go so far into the pipette so it will not overfill

4. Immediately upon filling the pipette, place a finger over the wide end of the pipette, with your other hand squeeze the reservoir slightly, seat the pipette into the reservoir; remove yourfinger from the pipette, then let go of the reservoir. A slight vacuum is created in the reservoir and the blood will be sucked into the reservoir. Squeeze the reservoir several times to mix the blood with the saline solution. The blood and saline mixture may be used immediately, or it may stand before use.

5. Charge the hemacytometer. To charge the hemacytometer, place the cover glass on the raised surfaces of the hemacytometer. Remove the pipette from the reservoir and insert the other end of the pipette into the reservoir. Squeeze out several drops of the mixture into a dry cotton ball. Place a small drop of the mixture on the polished counting surface of the hemacytometer next to the edge of the cover glass. Capillary action will suck the mixture under the cover glass. The chamber is properly filled when the polished counting surface is evenly filled with none of the mixture running into the moat around the counting surface.

6. Place the hemacytometer under the low power objective and locate the grid lines. Figure 26.1 shows the grid line arrangement of the hemacytometer. Note on the drawing the five areas that have the "R" marked on them. These five areas have each been subdivided into sixteen smaller grids. Switch to high power and count the red blood cells in each of the five grids. On high power, each grid area will almost fill the field. With a mechanical hand counter, count the cells in each set of sixteen smaller grids. To avoid over counting, count those cells that touch the grid lines on the left and top boundaries. Do not count those cells that touch the grid lines on the right and bottom boundaries.

7. To determine the number of red blood cells per cubic millimeter of blood, add the number of cells counted in the five grid areas and then add four zeros to the end of the number, i.e., multiply by 10,000.

8. Once you have finished your count; place your Unopette for red blood count into the bio-hazard container.

9. Record your total red blood cell count below.

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  • Sini
    How many rbc counted in a high power objective?
    7 years ago
  • karita
    How do we use unopette for red blood cells count?
    6 years ago
  • sinit
    How are abo blood cells counted to avoid counting them twice?
    6 years ago

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