RBC (nuclear) scan

An RBC nuclear scan is a group of tests using small amounts of radioactive material to mark (tag) red blood cells (RBCs). The body is then scanned to detect the location and flow of the tagged RBCs (see also nuclear ventriculography).

The exact procedure may vary slightly depending on the reason for the scan (the suspected problem).

The RBCs are tagged with radioisotope in 1 of 2 ways.

First, a sample of blood may be withdrawn from the person in the standard venipuncture method (similar to getting a sample for a blood test). In the laboratory, the RBCs are separated from the rest of the blood components and mixed with the radioisotope. A short time later these tagged RBCs are reinjected into a vein.

The second method involves injection of a medication that sensitizes the RBCs in the body, which is a complex chemical reaction that permits the RBCs to accept the radioisotope (attach the isotope to the cell membrane). The isotope is injected into a vein 15 or 20 minutes later.

Scanning may be performed immediately, after a delay, or a series of scans may be performed. The whole body or only particular locations may be scanned depending on the indications for the test. The person lies on a table while the scanner detects the location and amount of radiation emitted by the tagged RBCs.

You must sign a consent form. You will wear a hospital gown, and remove jewelry or metallic objects before the scan.

There will be a sharp prick from the needles used for blood withdrawal or injection. You will not feel the radioisotope and the imaging, but the table may be cold or hard. You must lie still during the scan.

This test is most often performed to locate the site of bleeding in patients who have blood loss from the colon or small bowel. A variation on this test may be performed to check the function of the heart (ventriculogram).

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