pcv calculation formula | complete measurements of packed cell volume

MEASUREMENT OF PACKED CELL VOLUME (PCV) | pcv calculation formula | complete measurements of packed cell volume | (HAEMATOCRIT)

This is the measure of the relative mass of erythrocytes present in a sample of a whole blood.

image result of pcv calculation formula | complete measurements of packed cell volume
The packed cell volume (PCV) is the measure of the ratio of the volume occupied by the red cells to the volume of whole blood in a sample of capillary, venous, or arterial blood. The ratio is measured after appropriate centrifugation6,10 and is expressed as a decimal fraction.

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AIM: The packed cell volume or haematocrit is used to calculate the mean cell volume (MCV). These red cell indices are used in the investigation of anaemia

SPECIMEN: Well mixed, well oxygenated EDTA anti-coagulated blood or capillary blood can be used.

EQUIPMENTS      REQUIRED:-      Micro-haematocrit      centrifuge -capillary tubes, sealant.

PRINCIPLE;   The   Red   blood   cells   in   the   capillary tube   are separated by centrifuge force of gravity.

LABORATORY EQUIPMENTS | pcv calculation formula | complete measurements of packed cell volume

pcv calculation formula | complete measurements of packed cell volume


Using a heparinized capillary (red tipped); collect a capillary blood filling 3/4 of the tube.

Seal the unfilled end using a sealant material or heat seal the capillary using a small flame from a spirit lamp or pilot flame of a Bunseii burner, rotating the end of the capillary in v the flame until it. get bulk end.

Carefully    located    the    filled    capillary    ion    one of   the numbered slots of the micro-haematocrit rotor with the sealed end against the rim gasket (to prevent breakage).

Write the number of the slot on the patients form. Position   the   safety  cover  and   the   lid   carefully  to   avoid dislodging the tubes.

Centrifuge for  12,000 revolution per min (10,000 rpm) for it< Sminutes

Immediately after centrifuge, read the PCV making sure that there has been no leakage of blood from the capillary or breakage.

HOW TO READ PCV PCV is read using Hand-held micro-haematocrit reader Position the tube in slot so that the base line of the reader (zero line) interests base of red cell.

pcv calculation formula | complete measurements of packed cell volume

Move   tube   holder   so   that   the   top   line   (hundred ‘ line) interests top of plasma.

Adjust knob   so that the middle line interests top of red cells.

Read the percentage of PCV on the scale.


Use a ruler to measure the height of the    total column of blood (top of plasma to bottom of red cell column) in rnrn.

Read out the height of the cell column

Then calculate the PCV.

Thus PCV = Height of red cells column (mm) height of total column (mm)

Example: If the height of the packed cell whole sample in mm are 19mm and 49mm respectively, then the PCV can be obtained-using the above as follows.

PCV =19  = 0.388L Packed cells/L Whole blood

49 = 39%

Packed cell volume is expressed in percentage (%) and it is age, gender and altitude dependent it’s accuracy can be affected by Specimen collection

The quality of capillary tube used

The time and speed of centrifuge

Method used for reading the result The reference ranges includes:

Adult male        40- 54%

Adult females   36 – 47%

Infants              44 – 64% •


AIM: A white cell count (WBC) is used to investigate infections and unexplained fever and .to  monitor treatments  which  can cause leucopoenia

pcv calculation formula | complete measurements of packed cell volume

SPECIMEN:   EDTA   anti-coagulate   blood   sample   or   capillary blood samples can be used.

EQUIPMENT:  Counting chamber (Haemacytorneter),  Counting Chamber cover glasses, pipettes, Hand counter.

READGENT: WBC diluting fluid such as Turks solution

Turks solution: Is made up of 2mls of Glacial acetic acid 98mls of water tinge with


– Count the cells in the four large corners squares of the chamber and also the cells lying on the lines of two side of each large square.

Report the number of white blood cells per liter of blood using this method.

If you count four large squares, multiply the sum of the four squares by 50.

If you count two adjacent large squares, multiply the sum. of the tow squares by 100.

After    performing    the    count,    before    the    sample    dries, dismantle the chamber, wash and dry it.

Store it with the cover glass in a safe place.

White blood cell count is expressed in cell/mm3 and normal ‘ranges varies with age and gender. Its references ranges includes:

Children at 1 year  6,000 – 18,000 cellls/mrn3

Children at 4-7years   5,000 – 15,000 cells/mm3
Adults     4,000 – 10000 cells/rnrn3

Raised WBC (Leucoytosis) could be as a result of

Acute infection


Poisoning etc. Reduced WBC (Leucopenia) could be as result of

Viral, Bacterial or parasitic infections e.g. HIV/AIDS

Vitamin 612 deficiencies

Ionizing radiation.