Routine blood test is also called as the complete blood count or CBC.
It is one of the most common test performed.

What does CBC measure?
CBC usually is a measure of different kinds of cells present in the blood.
The cells normally present in the blood are:
Red blood cells (RBC) – These cells contain hemoglobin and are responsible for carrying oxygen throughout the body. Decrease in RBC may cause fatigue and breathlessness.
White blood cells (WBC) – These cells are the guardians of the body and fight against infection. Any abnormality in the level of WBC may be an indication of infection.
Platelets– These are blood cells that are responsible for clotting of the blood when we get hurt. Decrease in the platelet count may cause excessive bleeding and any abnormal increase in the platelet count may be responsible for sludging of the blood and slowing of circulation in particular organs of the body. Platelet counts may also increase in conditions like juvenile rheumatoid arthritis and other autoimmune disorders.

How is CBC measured? Blood is collected either by a finger prick or a small sample of blood is collected from an accessible vein usually in the arm with a needle and a syringe. The part of the body from which blood is to be collected is cleaned with a sprit swab and then pricked with a needle. The collected blood sample is mixed with a chemical to prevent it from clotting and analyzed either under a microscope or under a computerized analyzer. The number of WBC, RBC and platelets are determined and the results are usually ready in a few hours.