A complete blood count (CBC) is a blood test used to evaluate your overall health and detect a wide range of disorders, including anemia, infection, and leukemia.
Your doctor may order this test for a variety of reasons. It may be a part of a routine check-up or screening, or as a follow-up test to monitor certain treatments. It can also be done as a part of an evaluation based on a patient’s symptoms.
During a CBC, a lab technician will draw blood from a vein, typically from the inside of your elbow or from the back of your hand. The test will take only a few minutes.
The technician cleans your skin with an antiseptic wipe. Then places an elastic band, or tourniquet, around your upper arm to help the vein swell with blood. Later, inserts a needle into your vein and collects a blood sample in one or more vials.
A CBC is not a definitive diagnostic test. Blood cell counts that are too high or too low could signal a wide variety of conditions. Specialized tests are needed to diagnose a specific condition. Conditions that could cause an abnormal CBC and may require additional testing include iron or other vitamin and mineral deficiencies, bleeding disorders and any heart disease.