A WBC scan is a nuclear scan (radioisotope test) using white blood cells (WBCs) that are tagged with radioactive material to locate areas of infection or inflammation.

Nuclear WBC scanning uses small amounts of radioactive materials (radioisotopes) that are attached to a sample of white blood cells. These tagged white cells are returned to the body, and accumulate in areas of inflammation or infection such as an abscess. The radiation emitted can be detected by a scanner, revealing hidden sites of infection or inflammation.

One or two vials of blood are withdrawn from a vein. The white blood cells are separated from the rest of the blood sample and are mixed with a small amount of a radioisotope (indium-111). About 2 or 3 hours later, these tagged white blood cells are returned to your body through injection into a vein.

Six to 24 hours later, your body is scanned. You lie on a table. The scanner looks like an x-ray machine, and detects radiation that is emitted from within the body by the radioactive white blood cells. It converts the detected radiation into an image that can be viewed on a screen or recorded on film. 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.

After the test is completed, no recovery time or special precautions are necessary. You typically may resume a normal diet, activity, and medications.

There is usually no need for fasting, special diets, or preliminary medications. You must sign a consent form. You will wear a hospital gown or be allowed to wear loose fitting clothing without metal fasteners. Remove jewelry, dentures, or metal before the scan.

The health care provider will occasionally request that antibiotics be stopped before this test.

There is a sharp prick from the needle during blood sampling and again when the blood is returned to you. The scan itself is painless, although the table that you are asked to lie on may be hard or cold. You do not feel the radioactive material.

WBC scan is most often performed when the health care provider suspects a hidden infection. It is particularly useful for suspected infection or inflammation within the abdomen. This test may be advised when there is suspected pyelonephritis, abscess, or osteomyelitis. It also may be advised when there is an unexplained fever, particularly after surgery.