Usually, blood is taken from an artery. The blood may be collected from the radial artery in the wrist, the femoral artery in the groin, or the brachial artery in the arm.
The health care provider may test circulation to the hand before taking a sample of blood from the wrist area.
The health care provider will insert a small needle through the skin into the artery. You can choose to have numbing medicine (anesthesia) applied to the site before the test begins.
In some cases, blood from a vein may be used.
After the blood is taken, pressure is applied to the site for a few minutes to stop the bleeding. The health care provider will watch the site for signs of bleeding or circulation problems.
The sample must be quickly sent to a laboratory for analysis to ensure accurate results.