Complete blood count - series

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A CBC requires a small blood specimen. In most cases, blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. Sometimes, blood is obtained from a fingerprick.

Preparation: The skin should be cleaned with alcohol or iodine before the test. The patient should be seated comfortably or reclining.

How the test will feel:

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. After the blood is drawn, there may be some throbbing.

Although the CBC test is very safe, any blood drawing has a very small risk of complication, including:

  • Oozing of blood from one puncture site
  • Fainting or feeling lightheaded
  • Hematoma (blood accumulating under the skin)
  • Multiple punctures to locate veins
  • Infection (a slight risk any time the skin is broken)

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