The procedure for this test may vary a little. This depends on the reason for the scan.

The RBCs are tagged with radioactive material in 1 of 2 ways.

The first method involves removing blood from a vein. The RBCs are separated from the rest of the blood sample. The cells are then mixed with the radioactive material. The cells with the radioactive material are considered "tagged." A short time later the tagged RBCs are injected into one of your veins.

The second method involves an injection of a specific medicine. The medicine allows the radioactive material to attach to your red blood cells. The radioactive material is injected into a vein 15 or 20 minutes after you receive this medicine.

Scanning may be done right away or after a delay. For the scan, you will lie on a table under a special camera. The camera detects the location and amount of radiation given off by the tagged cells.

A series of scans may be done. The specific areas scanned depend on the reason for the test.

You will need to sign a consent form. You put on a hospital gown and take off jewelry or metallic objects before the scan.

You may feel a little pain when the needle is inserted to draw blood or to give the injection. Afterward, there may be some throbbing.

The radioactive material is painless. Some people may have discomfort from lying on the hard table.

This test is most often done to find the site of bleeding such as from the colon or other parts of the gastrointestinal tract.

A similar test called a ventriculogram may be done to check heart function.

A normal exam shows no rapid bleeding from the gastrointestinal tract.

There is active bleeding from the gastrointestinal tract.

Slight risks from having blood drawn include:

• Fainting or feeling lightheaded
• 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. This may include anaphylaxis if the person is very sensitive to the substance.

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.

Most nuclear scans (including an RBC scan) are not recommended for women who are pregnant or breastfeeding.

Scans may need to be repeated over 1 or 2 days to detect gastrointestinal bleeding.

Bleeding scan; Tagged RBC scan; Hemorrhage - RBC scan

Bezobchuk S, Gralnek IM. Middle gastrointestinal bleeding. In: Chandrasekhara V, Elmunzer J, Khashab MA, Muthusamy VR, eds. Clinical Gastrointestinal Endoscopy. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 17.

Chiang KJ, Saillant NN, Hodin R, Acute gastrointestinal hemorrhage. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 21st ed. Philadelphia, PA: Elsevier; 2022:chap 47.

DeGeorge LM, Nable JV. Gastrointestinal bleeding. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 26.

Updated by: Jason Levy, MD, FSIR, Northside Radiology Associates, Atlanta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.