Manual rbc count formula, procedure by Neubauer chamber

Learn about “Manual rbc count procedure” using Neubar chamber..

Red blood cells are an important part of our blood. It has hemoglobin protein which carries oxygen (Oxygenation) from the lungs and is transported to the different body parts like the brain, kidney, skin, hands, feet, etc., therefore, a red blood cell count test is important in hematology.

In return, it brings carbon dioxide (CO2) from these parts to the lungs (deoxygenation).

Therefore red blood cell count is necessary for the identification of oxygenation percentage in the blood. This test is mostly performed by automation method but, some clinical laboratories use the manual method of red blood cell count.

what are the requirements of Red blood cell count test?

Following are the requirements of the red blood cell count test.

  1. Red blood cell pipette
  2. Improve Neubaur chamber
  3. Red blood cell diluting fluid
  4. Microscope

Manual red blood cell count procedure

Following steps performed during RBC count

  1. Draw and the mix the blood in RBC pipette up to 0.5.
    • Note: Care should be taken note to have bubble in blood column.
  2. Now draw the diluting fluid up to 201 mark.
  3. Gently rotate the pipette between thumb and forefinger.
  4. Alternatively prepare 1/200 dilution of blood by mixing 20 micro litter blood with 4 ml diluting fluid.
  5. Place the cover slip on neubaur chamber.
    • Note: Correct placement indication is that, diffraction rings are seen on either side.
  6. Discard first 4 to 5 drops from rbc pipette before charging neubaur chamber.
  7. Charge one side of chamber by introducing small drop of diluted blood. The sample will move by capillary action.
  8. Wait for two minutes to allow the RBC cell to settle.
  9. Count the RBC at 40X objective in central large sqaure and four other corner . Count at least 500 cells.
    • Note: If there is not sufficiant cell in these corner, add more square corner.

Advantage of manual red blood cell count test

The advantage of the manual method is.

  1. It is cheap.
  2. It is reliable.
  3. Result accuracy is more.

The disadvantage of manual red blood cell count test

The disadvantage of the manual method is.

  1. It is more time consumig.
  2. It is cumbersome in busy laboratories.
  3. There are more chance of errors in manual counting.

Manual red blood cell count formula

Following is the RBC calculating formula.

TRBC = N* 200* 106/ 0.1

  • N= is the number of RBC in square areas.
  • 0.1= volume of central square areas.

Note: we can calculate MCV (mean corpuscular volume) when we have an RBC count.

Neubauer chamber rbc count calculation

Neubauer chamber area is 3 * 3 mm, devided into 9 squares. Each square is 1 mm 2. The central area of the Neubauer chamber is further divided into 25 squares.

Depth of chamber is = 0.1 mm
Thus volume in the central square area is = Length * breadth * height
Volume = 1 * 1 * 0.1 = 0.1 mm3 , ( 1 mm3 = 1 micro litter )
Number of cells in the central area is “N” . 0.1 area has “N” number of cells.
1 micro litter has N / 0.1 cells, while the dilution used is 1/200.

tRBC = N / 0.1 * 200 *10 6

Red blood cell count high causes

Following are the causes of high RBC count in the blood.

  1. Polycythemia
  2. Smoking
  3. Kidney tumor which synthesis more erythropoiten.
  4. Polycythemia vera
  5. Pulmonary disease
  6. Dehydration

Red blood cell count low causes

  1. Bone marrow infiltration
  2. Anemia
  3. Leulemia
  4. Iron deficiancy

Red blood cell count normal range in male and female

  • RBC reference range in Male = 4 – 5 * 10 12 / Litter
  • RBC reference range in Female = 3 – 4 * 10 12 /Litter

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