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Alternative names Return to top
Erythrocyte count; Red blood cell countDefinition Return to top
This is a blood test that measures the number of red blood cells (RBCs). The RBC count is almost always part of the CBC (complete blood count) test.How the test is performed Return to top
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test Return to top
No special preparation is necessary for adults.How the test will feel Return to top
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.Why the test is performed Return to top
This test can help identify anemia (low hemoglobin) as well as other conditions affecting the red blood cells.Normal Values Return to top
RBC (varies with altitude):What abnormal results mean Return to top
Abnormal RBCs have a shorter-than-normal life span. Trauma within the blood vessels, such as that caused by artificial heart valves or peripheral vascular (blood vessel) disease, can damage RBCs. An enlarged spleen, as can be caused by portal hypertension or leukemia, may remove normal red cells along with aging ones.
Higher-than-normal numbers of RBCs may indicate:
What the risks are Return to top
Special considerations Return to top
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Page last updated: 28 October 2004 |