Blood sample - arterial
An arterial stick is collection of blood from an artery for laboratory testing.
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 area is cleaned with antiseptic and a needle 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 a sufficient sample of blood. Pressure is applied to the puncture site for 5 to 10 minutes to stop the bleeding. The person will be monitored during this time to make sure the bleeding stops.
How to prepare for the test
Preparation varies with the specific test performed.
For infants and children:
The preparation you can provide for this procedure depends on your child’s age and previous experience. For specific information regarding how you can prepare your child, see the following topics:
- infant test or procedure preparation (birth to 1 year)
- toddler test or procedure preparation (1 to 3 years)
- preschooler test or procedure preparation (3 to 6 years)
- schoolage test or procedure preparation (6 to 12 years)
- adolescent test or procedure preparation (12 to 18 years)
How the test will feel
Puncture of the artery may be somewhat more uncomfortable than puncture of a vein, and requires firm pressure over the site after it is drawn.
When the needle is inserted, most people feel moderate discomfort or pain. Afterward, there may be some throbbing. The arterial stick is more painful than venipuncture because arteries are deeper than veins, have thicker walls, and have more nerves.
Why the test is performed
Blood transports oxygen, food, waste products, and other materials within the body. It is also regulates body temperature, fluids, and acid-base equilibrium.
Blood is made up of a fluid portion (plasma) and a cellular portion. Plasma contains various substances dissolved in the fluid. The cellular portion consists primarily of red blood cells, but also includes white blood cells and platelets.
Because blood serves multiple functions within the body, tests on the blood or its components may give valuable clues in the diagnosis of a multitude of medical conditions.
Arterial blood differs from venous blood primarily in its content of dissolved gases. Testing of arterial blood shows the make-up of the blood before any of its contents are used by the body tissues.
See specific tests, particularly the arterial blood gas test.
What abnormal results mean
An arterial stick is performed to obtain arterial blood samples. Arterial blood samples are primarily performed to measure arterial blood gases (which may indicate breathing problems or metabolic disorders). However, arterial sticks may occasionally be performed to obtain blood culture or serum chemistry samples.
What the risks are
- fainting or feeling light-headed
- excessive bleeding
- hematoma (blood accumulating under the skin)
- infection (a slight risk any time the skin is broken)
There is a slight risk of damage to surrounding tissues while the blood is obtained. Specimens are also obtained from lower-risk sites, and techniques are used to minimize tissue damage.
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. If blood is easier to obtain from a particular location or side, it is helpful to let the person drawing the blood know before starting the test.
by David A. Scott, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.