Principle: Blood is diluted 1 in 20 in a filtered solution of ammonium oxalate reagent which lyses the red cells, platelets are counted microscopically using an improved neubauer ruled counting chamber and the number of platelets per liter of blood calculated.
- I measured 0.38ml of filtered ammonium oxalate diluting fluid and dispensed it into a tube.
- 02ml of well – mixed anticoagulated venous blood wasn added into the tube and mix.
- Assembled the counting chamber
- Re-mixed the diluted blood sample using a capillary Pasteur pipette, I filled one of the grids of the chamber with the sample.
- I left the chamber undisturbed for 20 minutes. To prevent drying of the fluid, placed the chamber in a Petri – dish and covered with a lid.
- Dried the underside of the chamber and placed it on the microscope stage. Using the 10 x objective, focus the rulings of the grid and bring the central square of the chamber into view. Change to the 40 x objective and focus the small platelets. They were seen as small bright fragments
- I counted the platelets in the small squares
Report the number of platelets in a 1 liter of blood