LAB - RED BLOOD CELL COUNT

Introduction:

Red blood cell counting is an important diagnostic test towards observation of peripheral blood film. Changing in total number of red blood cells is related to physiological or pathological method. Increase in red blood cell is related to polycythaemia cases while decrease of total number of red blood cells is related to anaemia cases.

Equipments:

1. Formal citrate dilution solution
2. Neubauer chamber
3. Red blood cell Thoma pipette
4. Microscope
5. Blood sample

Reagents:

Dilution solution: Formal citrate

1. 1% (l/l) Formalin (40% Formaldehyde) in 3% Trisodium Citrate.
2. 1-2 drops of Brilliant Cresyl blue (1% in isotonic saline) in each litre of formal citrate solution.

Procedure:

1. Using a red blood cell Thoma pipette draw well mixed venous blood or capillary blood and fill till the 0.5 mark. Clean the tip of the tube.
2. Draw diluting fluid to the 101 mark.
3. Shake and mixed well for 5 minutes.
4. Discard the first four drops of mixture and gently fill in the mixture into the Neubauer chamber.
5. Under 10x magnification, scan to ensure even distribution.
6. Count the red blood cells using 40X objective in the 80 smallest squares as indicated in the diagram of the chamber.

Normal range:

Men                 :           4.5-6.5 x 10¹² / L

Women            :           3.8-5.8 x 10¹² / L

Babies             :           4.0-6.0 x 10¹² / L

Questions:

1. State FOUR (4) sources of error and indicate if the cell count would be falsely increased or decrease.
2. What is the purpose to dilute the blood with formal citrate?