Indium-labelled WBC scan

Definition

A radioactive scan detects abscesses or infections in the body by using a radioactive material. An abscess occurs when pus collects due to an infection.

Alternative Names

Radioactive abscess scan; Abscess scan; Indium scan; Indium-labeled white blood cell scan; WBC scan

How the Test is Performed

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 (radioisotope) 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 scan to see if white blood cells have gathered in areas of your body where they would normally not be located.

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 after 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:

• Gallium (Ga) scan within the past month
• Hemodialysis
• Hyperglycemia
• Long-term antibiotic therapy
• Steroid therapy
• Total parenteral nutrition (through an IV)

How the Test will Feel

Some people feel a little pain when the needle is inserted to draw blood. Others feel only a prick or sting. Afterward, there may be some throbbing.

The nuclear medicine scan is painless. It may be a little uncomfortable to lie flat and still on the scanning table. This most often takes about an hour.

Why the Test is Performed

The test is rarely used today. In some cases, it may be helpful when doctors cannot localize an infection. The most common reason it is used is to look for a bone infection called osteomyelitis.

It is also used to look for an abscess that may form after surgery or on its own. Symptoms of an abscess depend on where it is found, but may include:

• Fever that has lasted a few weeks without an explanation
• Not feeling well (malaise)
• Pain

Other imaging tests such as an ultrasound or CT scan are often done first.

Normal Results

Normal findings would show no abnormal gathering of white blood cells.

What Abnormal Results Mean

A gathering of white blood cells outside of the normal areas is a sign of either an abscess or other type of inflammatory process.

Abnormal results may include:

• Bone infection
• Abdominal abscess
• Anorectal abscess
• Epidural abscess
• Peritonsillar abscess
• Pyogenic liver abscess
• Skin abscess
• Tooth abscess

Risks

The risks of this test include:

• Some bruising may occur at the site of injection.
• 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.

Pregnant women and children are more sensitive to the risks of radiation.

References

Chacko AK, Shah RB. Emergency nuclear radiology. In: Soto JA, Lucey BC, eds. Emergency Radiology: The Requisites. 2nd ed. Philadelphia, PA: Elsevier; 2017:chap 12.

Cleveland KB. General principles of infection. In: Azar FM, Beaty JH, Canale ST, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 20.

Matteson EL, Osmon DR. Infections of bursae, joints, and bones. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 256.