The average volume or size of red blood cells in a blood sample is referred to as Mean Corpuscular Volume (MCV). The MCV blood test is often a part of the Complete Blood Count (CBC) test and it’s also commonly known as CBC with Differential. Corpuscular means blood cells and there are mainly 3 types - red blood cells, white blood cells and platelets. Red blood cells (erythrocytes) or RBCs carry oxygen from the lungs to every cell in our body. The cell metabolism depends upon the oxygen it receives. The RBCs which carry oxygen may be too small or too large and this can cause blood disorders or other medical conditions. The MCV blood test together with CBC test is done as part of routine screening of any blood disorder and health check- ups. A person complaining of fatigue, breathlessness, cold hands and feet, pale skin and unusual bleeding may need to undergo the MCV blood test.