What is Packed Cell Volume (PCV) or Hematocrit? Uses and Mmethods for Estimation of Packed Cell Volume (PCV)
Learn about Packed Cell Volume (PCV), also known as hematocrit (HCT), its uses in detecting anemia and polycythemia, and methods for estimation. Discover why the micro method is preferred for its accuracy and efficiency.

Packed cell volume (PCV), also known as hematocrit (HCT) or erythrocyte volume fraction, represents the proportion of red blood cells in a sample of anticoagulated blood after centrifugation. This measurement reveals the relative amount of red blood cells in comparison to plasma. PCV is typically expressed either as a percentage of the total blood volume or as a decimal fraction. For instance, a PCV of 40% indicates that 40 milliliters of cells are present in 100 milliliters of blood. This metric is crucial in diagnosing and monitoring various conditions. An elevated PCV can signify an increased number of red blood cells or a reduction in plasma volume, such as in cases of dehydration. Conversely, a decreased PCV may indicate anemia, where there is a reduction in red blood cell production, increased destruction of red blood cells, or dilution of blood cells due to an increase in plasma volume, often observed during pregnancy or other conditions causing hemodilution.
Uses of PCV
- Detection of Anemia or Polycythemia: PCV is essential for identifying the presence of anemia (a condition characterized by a deficiency of red blood cells) or polycythemia (an excess of red blood cells).
- Estimation of Red Cell Indices: PCV aids in calculating red cell indices, such as mean cell volume (MCV) and mean corpuscular hemoglobin concentration (MCHC), which are crucial for diagnosing various hematological conditions.
- Verification of Hemoglobin Levels: PCV is used to verify the accuracy of hemoglobin measurements, as there is a standard relationship: Hemoglobin in grams per deciliter (g/dL) multiplied by 3 equals the PCV.
Methods for Estimating PCV
There are two primary methods for estimating PCV; macro method (Wintrobe method) and micro method (microhematocrit method).
- Macro Method (Wintrobe Method): This traditional method involves using a larger volume of blood.
- Micro Method (Microhematocrit Method): This method is preferred due to its rapidity and convenience. It requires only a small amount of blood, such as capillary blood from a skin puncture, and allows for the testing of multiple samples simultaneously. The micro method is also more accurate, as it minimizes plasma trapping within the red cell column.
The micro method's efficiency and accuracy make it the preferred choice in clinical settings, ensuring reliable results with minimal blood sample requirements.
Cite this page:
- Comment
- Posted by Dayyal Dg.