Venipuncture

In medicine venipuncture or venepuncture is the process of obtaining a sample of venous blood. Usually a 5 ml to 25 ml sample of blood is adequate depending on what blood tests have been requested. In many circumstances it will be done by a phlebotomist, although nurses, doctors and other medical staff are also trained to take blood.

Blood is most commonly obtained from the median cubital vein, on the anterior forearm.This vein lies close to the surface of the skin, and there is not a large nerve supply.Minute quantities of blood may be taken by fingersticks sampling and collected from infants by means of a heel stick or from scalp veins with a butterfly needle.Phlebotomy is also the treatment of certain diseases such as hemochromatosis and primary and secondary polycythemia.