Health Encyclopedia - Test
A white blood cell (WBC) scan is an imaging test that uses a radioactive material(called a tracer) to look for infection or inflammation in the body. It is a type of nuclear scan
How the test is performed
Blood will be taken from one of your veins. White blood cells are separated from the rest of the blood sample. They are then mixed with a small amount of a radioactive material (radioisotope) called indium-111. These cells are considered "tagged."
The tagged white blood cells are returned to your body through an inject into the vein 2-3 hours later. The tagged cells gather in areas of inflammation or infection.
Your body will be scanned 6-24 hours later. For the scan, you will lie on a table. The scanner looks like an x-ray machine. It pick ups radiation given off by the tagged white blood cells. A computer creates an image from the radiation that is picked up and displays it on a screen.
The scan takes about 1 or 2 hours. The scanner is usually located in a hospital, but often the test can be performed on an outpatient basis.
You do not have to take any special steps after the test is over. You may go back to your normal diet, activity, and medicines.
How to prepare for the test
You do not need special preparation for this test. You must sign a consent form.
You will need to wear a hospital gown or loose clothing without metal zippers or snaps. You will need to take off jewelry, dentures, or anything with metal before the scan.
The health care provider may ask that you stop taking antibiotics before this test.
Tell your health care provider if:
- You have had a gallium scan within the previous month.
- You are receiving dialysis, total parenteral nutrition (through an IV), or steroid therapy.
- You have hyperglycemia.
- You are taking long-term antibiotics.
This procedure is NOT recommended if you are pregnant. Tell your health care provider if you are pregnant or trying to become pregnant. Women of childbearing age (before menopause) should use some form of birth control over the course of this procedure.
How the test will feel
You will feel a sharp prick from the needle when the blood sample is taken and again when it is returned to your vein. The scan itself is painless. The the table that you are asked to lie on may be hard or cold. You do not feel the radioactive material.
Why the test is performed
WBC scan is done to look for a hidden infection. It is particularly useful if your doctor suspects there is an infection or inflammation in the abdomen or bones.
Your doctor may suggest this test if you may have an abscess, osteomyelitis, or unexplained fever, particularly after surgery.
A normal result means that tagged cells have not gathered abnormally.
What abnormal results mean
What the risks are
There is a small exposure to radiation from the radioisotope. The radiation from these materials is very slight, and the materials break down in a very short time. Nearly all radioactivity is gone within 1 or 2 days. There are no known cases of injury from exposure to radioisotopes. The scanner does not give off any radiation.
Due to the slight radiation exposure, most nuclear scans (including WBC scan) are not recommended for women who are pregnant or breastfeeding.
Veins and arteries vary in size so it may be harder to get a blood sample from some people than others.
Other risks small risks from having blood include:
- Too much bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Segerman D, Miles KA. Radionuclide imaging: general principles. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 7.
Wilson DJ, Berendt AR. Bone and soft tissue infection. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 51.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.