Packed cell volume (PCV) is the volume occupied by the red cells when a sample of anticoagulated blood is centrifuged. It indicates relative proportion of red cells to plasma. PCV is also called as hematocrit or erythrocyte volume fraction. It is expressed either as a percentage of original volume of blood or as a decimal fraction.
USES OF PCV
- Detection of presence or absence of anemia or polycythemia
- Estimation of red cell indices (mean cell volume and mean corpuscular hemoglobin concentration)
- Checking accuracy of hemoglobin value (Hemoglobin in grams/dl × 3 = PCV).
There are two methods for estimation of PCV: macro method (Wintrobe method) and micro method (microhematocrit method). Micro method is preferred because it is rapid, convenient, requires only a small amount of blood, capillary blood from skin puncture can be used, and a large number of samples can be tested at one time.
This method is also more accurate as plasma trapping in red cell column is less.