What Is a Complete Blood Count (CBC)?

Complete Blood Count (CBC)

Blood is made up of different parts, such as red blood cells, white blood cells, and platelets. Red blood cells carry oxygen all through your body. White blood cells defend it against germs that try to make you sick. And platelets stick together to form a plug to stop bleeding if you get a cut. Doctors sometimes order blood tests to check a small blood sample. One type of blood test is called a complete blood count (CBC) because it helps doctors see how many red blood cells, white blood cells, and platelets are in someone's blood.