Blood is drawn from a vein, most often on the inside of the elbow or the back of the hand.
The site is cleaned with germ-killing medicine (antiseptic).
The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle.
The elastic band is removed from your arm.
The puncture site is covered to stop any bleeding.
The blood sample is then sent to a lab. There the white blood cells are tagged with a radioactive substance called indium. The cells are then injected back into a vein through another needle stick.
You will need to return to the office 6 to 24 hours later. At that time, you will have a nuclear medicine scan to see if white blood cells have gathered in areas of your body where they would not be normally.
How to Prepare for the Test
Most of the time you do not need special preparation. You will need to sign a consent form.
For the test, you will need to wear a hospital gown or loose clothing. You will need to take off all jewelry.
Tell your provider if you are pregnant. This procedure is NOT recommended if you are pregnant or trying to become pregnant. Women of childbearing age (before menopause) should use some form of birth control during the course of this procedure.
Tell your provider if you have or had any of the following medical conditions, procedures, or treatments, as they can interfere with test results:
There is always a slight chance of infection when the skin is broken.
There is low-level radiation exposure.
The test is controlled so that you get only the smallest amount of radiation exposure needed to produce the image. Most experts feel that the risk is very low compared with the benefits.
Pregnant women and children are more sensitive to the risks of radiation.
Hutton BF, Segerman D, Miles KA. Radionuclide imaging. In: Adam A, Dixon AK, Gillard JH, et al. eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 6th ed. New York, NY: Churchill Livingstone; 2014:chap 6.
Jason Levy, MD, Northside Radiology Associates, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.