Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood).

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

The blood sample is then sent to the lab where they isolate the white blood cells (WBCs), and tag them with the radioactive substance, indium. The cells are then reinjected through another venipuncture.

You will have an appointment to return after 24 to 48 hours for the nuclear medicine scan component of this test in which clustering of WBC's outside the liver, spleen and bone marrow will be identified.

You must wear a hospital gown and remove all jewelry.

Inform the health care provider if you are pregnant. This procedure is NOT advised if you are pregnant. If you are a premenopausal woman, you should use some form of birth control during the course of this procedure.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

The nuclear medicine scan is painless. There may be some discomfort lying flat and still on the scanning table for a short period of time.

This test is used to identify an abscess in the body when a person has signs and symptoms of sepsis, or your health care provider wants to know the cause of surgical complications.

White blood cells are the body's means of fighting infection, and this test enables your health care provider to follow these cells and see if they are accumulating around a site of infection. It is expected that there will be groupings of white blood cells in the liver, spleen, and bone marrow, but if groupings of cells exist elsewhere, an abscess or other inflammatory process is possible.