An arterial stick is the collection of blood from an artery for laboratory testing.
Blood sample - arterial
How the test is performed
Usually the blood is drawn from the wrist. However, it may also be drawn from the inside of the elbow, groin, or other artery. A heartbeat (pulse) is felt by pressing on the area above an artery. The doctor will usually check to make sure blood is flowing into the hand from the main arteries in the forearm (radial and ulnar arteries).
The area is cleaned with antiseptic and a needle is inserted. A small amount of anesthetic may be injected or applied before the needle is inserted. The blood will easily flow into the specially prepared (heparinized) syringe.
The needle is removed after there is enough of a blood sample. Pressure is applied to the puncture site for 5 - 10 minutes to stop the bleeding. You will be checked during this time to make sure the bleeding stops.
How to prepare for the test
Preparation varies with the specific test performed.
How the test will feel
Puncture of an artery may be somewhat more uncomfortable than puncture of a vein, because arteries are deeper than veins, have thicker walls, and have more nerves. Also, firm pressure must be placed over the site after the blood is drawn.
When the needle is inserted, most people feel moderate discomfort or pain. Afterward, there may be some throbbing.
Why the test is performed
Blood transports oxygen, food, waste products, and other materials within the body. It also regulates body temperature, fluids, and the balance of acids and bases.
Blood is made up of a fluid portion (plasma) and a cellular portion. Plasma contains various substances dissolved in the fluid. The cellular portion is made up mainly of red blood cells, but it also includes white blood cells and platelets.
Because blood has many functions within the body, tests on the blood or its components may give valuable clues to help doctors diagnose many medical conditions.
Blood in the arteries (arterial blood) differs from blood in the veins (venous blood) mainly in its content of dissolved gases. Testing arterial blood shows the make-up of the blood before any of its contents are used by the body tissues.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
An arterial stick is done to get blood samples from arteries. Arterial blood samples are mainly taken to measure arterial blood gases (which may indicate breathing problems or metabolic disorders). However, arterial sticks may sometimes be done to get blood culture or blood chemistry samples.
What the risks are
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Infection (a slight risk any time the skin is broken)
There is a slight risk of damage to nearby tissues when the blood is drawn. Blood can be taken from lower-risk sites, and techniques are used to minimize tissue damage.
If blood is easier to get from one location or side of your body, let the person who is drawing your blood know before starting the test.
Milzman D, Janchar T. Arterial puncture and cannulation. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 20.
Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.