The Packed Cell Volume (PCV) Test
1. Objective:
This is one of the oldest tests done in medical practice. The objective of this test was to determine the percentage of red blood cells (RBCs) in whole blood. It also helped to assess the blood’s capacity to carry oxygen.
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2. Principle:
The test was based on the principle that when blood was centrifuged, the red blood cells settled at the bottom of the tube, forming a packed column. The ratio of the packed RBC column to the total blood column gave the packed cell volume (PCV), expressed as a percentage.
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3. Materials:
• Microhematocrit capillary tubes
• Microhematocrit centrifuge
• Plasticine or sealing clay
• Microhematocrit reader
• Lancet
• Alcohol swab
• Cotton
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4. Procedure (Microhematocrit Method):
1. The fingertip was cleaned with an alcohol swab and pricked with a sterile lancet.
2. Blood was collected into the capillary tube, filling about three-fourths of its length.
3. One end of the tube was sealed with plasticine.
4. The tube was placed in the microhematocrit centrifuge with the sealed end outward.
5. The sample was centrifuged at 12,000 rpm for 5 minutes.
6. After centrifugation, three layers were seen — plasma at the top, buffy coat (WBCs and platelets) in the middle, and packed red cells at the bottom.
7. The PCV was read using a hematocrit reader and expressed as a percentage of the total blood column.
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5. Result:
The Packed Cell Volume (PCV) was found to be 45%.
(Normal range:
• Male: 40–54%
• Female: 37–47%)
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6. Uses:
• It was used to diagnose anemia, polycythemia, and dehydration.
• It helped to evaluate the blood’s oxygen-carrying capacity.
• It was used to monitor patients after blood loss or transfusion.
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7. Consultation:
If the PCV was low, consultation with a doctor was advised to check for anemia or nutritional deficiency.
© PUBLIC HEALTH ORBITAL

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