The document discusses packed cell volume (PCV) as a measure of the volume of blood occupied by red blood cells, detailing various methods for its estimation, particularly the Wintrobe method. It describes the procedure for using the Wintrobe tube and centrifuge, along with the interpretation of results based on the separation of blood components. Clinical implications of varying PCV levels are outlined, noting causes for both increased and decreased measurements.

1. Packed cell volume Estimation
Dr. Bimochan Poudel
B.V.Sc and A.H , AFU
Dr.Bimochan Poudel

2. PACKED CELL VOLUME (HEMATOCRIT)
• Hematocrit literally means “blood separation”
• Packed cell volume is the percentage of volume
of blood occupied by the red cells
• Methods used for determination of PCV
1. Macrohematocrit method (Wintrobes method)
2. Microhematocrit method
3. Electrical method
4. Indirect method
Dr.Bimochan Poudel

3. Wintrobes method for estimation of
PCV
• Apparatus required
– Wintrobes tube –
• It is 110mm long, narrow, thick walled tube with 3mm
internal bore
• Graduated from 0 to 10 cm with graduation on both sides
in ascending and descending order on 2 sides of tube
• Scale with the markings from 0 to 10 from above
downwards is used in ESR determination and from below
upwards is used for PCV determination
– Pasteur pipette
– Centrifuge
Dr.Bimochan Poudel

4. Wintrobes Tube
Dr.Bimochan Poudel

5. Dr.Bimochan Poudel

6. Dr.Bimochan Poudel

7. Dr.Bimochan Poudel

8. Dr.Bimochan Poudel

9. Procedure –
– 2ml of venous blood is collected and mixed with double
oxalate (ammonium oxalate and potassium oxalate) or EDTA
powder in the proportion of 1.5mg/ml
– Blood is drawn into Pasteur pipette and introduced in the
Wintrobes tube from the bottom to 0 or 10 mark above
– Place the Wintrobes tube in the centrifuge machine and other
Wintrobes tube filled with water on the opposite side so as to
balance it.
– Centrifuge the tube at the speed of 3000rpm for 30 minutes
– After 30 minutes stop the centrifuge, take out the tube and
note the readings
– Calculation –
• Hematocrit = [ Height of RBC’s in mm/Height of RBC and plasma] X
100
Dr.Bimochan Poudel

10. Zones separated after centrifugation
• Top layer – Plasma (48 – 52%)
– Normally amber or pale yellow colour
– yellow – jaundice
– Pink or red colour indicates – hemolysis
– creamy white – hyperlipidemia
– Brown coloured – meth hemoglobinemia
– Cloudy (increased viscosity) – Multiple myeloma
• Intermediate zone – Buffy coat – Zone of platelets and leukocytes (2% –
3% or 1mm thick)
– Greyish – white tan layer
– Smears prepared from buffy coat can be used to diagnose
• Sub leukemic leukemia
• LE cells
• Detection of plasma cells
• Hemoparasites
• Lower most zone or bottom layer – Zone of packed RBC’s (45% – 50%)
Dr.Bimochan Poudel

11. Dr.Bimochan Poudel

12. Clinical implications of PCV
• PCV is affected by the number of RBC’s, their size and plasma volume
• High PCV –
– increased number of RBC’s
– Increase in size of RBC
– Decrease in plasma volume
• Low PCV
– Decrease in number of RBC’s
– Decrease in size of RBC
– Increase in plasma volume
• Causes of increased PCV
– Polycythemia vera
– High altitudes
– Hypoxia conditions
– Lung and heart diseases
– Dehydration
– Burns (due to loss of plasma)
• Causes of decreased PCV
– Anemia
– Conditions with increased WBC’s
– long term illness,
– infection
– leukemia
– Lymphoma
– Hemodilution or overhydration
– Acute kidney disease – lower erythropoietin production leads to less RBC’s production by bone marrow
– Pregnancy
Dr.Bimochan Poudel