A white blood cell (WBC) scan is an imaging test that uses a radioactive material called a tracer. It looks for infection or inflammation in the body. It is a type of nuclear scan.
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 injected back into your body through a vein 2 to 3 hours later. The tagged cells gather in areas of inflammation or infection.
Your body will be scanned 6 to 24 hours later. You will lie on a table for the scan. The scanner, which looks like an x-ray machine, will pick up radiation given off by the tagged white blood cells. A computer creates an image from the radiation, which is picked up and displayed on a screen.
The scan takes about 1 or 2 hours. The scanner is most often located in a hospital. 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 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 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 table that you lie on may be hard or cold. You will not feel the radioactive material.
Why the Test is Performed
WBC scan is done to look for a hidden infection. It is very useful in looking for infection or inflammation in the abdomen or bones.
Your provider 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
Abnormal results may mean you have an active inflammation or infection. This could include a liver or abdominal abscess, or osteomyelitis of the bone.
You will be exposed to a small amount of radiation from the radioisotope. The materials break down very quickly. Almost all radioactivity will be gone within 1 or 2 days. 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.
Other risks from having blood drawn 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)
Very rarely, a person may have an allergic reaction to the radioisotope.
Hutton BF, Segerman D, Miles KA. Radionuclide and hybrid 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.
Rajashanker B, Whitehouse RW. Bone, joint and spinal Infection. 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 53.