Dr.Sidra Qaiser
Requirements:
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RBC's pipette
Neubauer's Chamber
Cover slip
Petri dish
Filter paper
Pricking needle
Spirit swab
Microscope
Platelet fluid (Rees Ecker) fluid comprising of
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Saponin (hemolysing agent)
Formaldehyde (antiseptic)
EDTA (Anti-coagulant)
Distilled water
= 0.5 gm
= 1 ml
= 1.5 gm
= 100 ml
 Normal Values:
 150,000- 4, 00, 000/cmm
 (1.5 -4 x 1011 /L)
 (150- 400 x 109/L)
Procedure:
 Using spirit swab clean the finger and prick it with a
sterile needle.
 Discard the first drop of blood and let the second drop
accumulate on the tip of the finger.
 Dip the tip of RBC pipette and suck the blood up to the
mark 0.5
 Now suck the platelet fluid up to mark 101.
 Mix the contents for 2-3 minutes.
 Placing a clean Neubauer's chamber under the high
power, charge it with the contents of the RBC pipette.
Before charging, discard few drops and do not forget to
place a cover slip.
 Place the Neubaeur's chamber in the petri dish lined
by the moist filter paper to prevent drying of the
contents for 15 -30 minutes.
 Now focus the chamber to look for the RBC square at
first under low power lens and then under high power
lens. Count the platelets in five small squares i.e 80
smallest squares using fine adjustment for critical
focusing which shows highly refractive silvery
appearance of platelets which are colourless, spherical
or oval shaped bodies. Generally they are seen in
groups.
Calculation:
 No. of platelets in 80 smallest squares = X
 No. of platelets in 1 smallest square = X/80
 Volume of 1 smallest square = 1 /20 x 1 /20 x 1 /10
= 1/4000 cmm
 Thus number of platelets in 1 cmm (1 ul) = X/80 x 4000
 Dilution factor = 1:200
 Thus number of platelets in 1 cmm of blood = X/80 x
4000 x 200
Precautions:
 Sucking of blood and fluid in the pipette should be
free of air bubbles.
 Do not let the contents in chamber to become dry.
 Count should be made under high power in sequence.
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