Microhaematocrit Method for estimation of packed cell volume (pcv) or hematocrit

Microhaematocrit Method  for estimation of packed cell volume (pcv) or hematocrit

Microhaematocrit Method  for estimation of packed cell volume (pcv)

Microhaematocrit Method

:- For this method, instead of Wintrobe's tubes, special non-graduated glass capillary tubes are used. These tubes are 7 cm in length and 1 mm in internal diameter.

-They can be purchased pre-coated internally with dried heparin for capillary blood. Plain capillaries (without heparin) can be used for anticoagulated blood

Specimen for Microhaematocrit Method

(Plain capillary tubes may be coated with heparin by filling them with 1:1000 dilution of heparin and drying at 56°C).

Procedure of Microhaematocrit Method

•  Take a heparinised capillary tube.
•  Fill it with blood by capillary action leaving 10 mm unfilled.
•  Seal the empty end by plastic seal or by heating onflame.
•  Centrifuge it in microhaematocrit centrifuge at 10,000g for 5 minutes

Measure the blood column by using a reading device which is usually a part of centrifuge.

Normal range:- Men: 40–52 % (0.4-0.52 L/L) Women: 37-47 % (0.37-0.47 L/L)

 

Advantages of Micro Method

i. Less amount of blood is required.

ii. Results are available within 5 minutes.

iii. Method is more accurate, trapping of plasma is less.

Sources of Errors in Macro and Micro Methods

i. Improper handling of sample.

ii. Calibration error.

iii. Unclean and contaminated tube.

iv. Improper centrifugation time.