A vein scan is a nuclear scanning test to detect blood clots in the deep veins of the legs (called deep vein thrombosis). Blood clots in certain large veins of the body can break loose and travel through the bloodstream to the lungs, blocking blood flow to a lung (pulmonary embolism). See an illustration of deep vein thrombosis.

During a vein scan, a radioactive tracer substance is injected into a vein in the arm. It travels through the bloodstream and accumulates at the site of a newly forming blood clot. Scans are done 10 to 90 minutes after the tracer is injected. A newly formed blood clot will show up on the pictures as a bright or "hot" spot.

Why It Is Done

A vein scan is done to detect newly forming blood clots, especially in the deep veins of the legs. Back to Top

How To Prepare

Before your vein scan, tell your doctor if:

• You are or might be pregnant.
• You are breast-feeding. Use formula (discard your breast milk) for 1 to 2 days after the scan until the radioactive tracer has been eliminated from your body.
• Within the past 4 days, you have had an X-ray test using barium contrast material (such as a barium enema) or have taken a medication (such as Pepto-Bismol) that contains bismuth. Barium and bismuth can interfere with test results.

You may be asked to sign a consent form before the test. Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

A vein scan is usually done by a nuclear medicine technologist. The scan pictures are usually interpreted by a radiologist or nuclear medicine specialist.

You will need to remove any jewelry that might interfere with the test. You may need to take off all or most of your clothes, depending on which area is being examined (you may be allowed to keep on your underwear if it does not interfere with the test). You will be given a cloth or paper covering to use during the test.

The technologist cleans the site on your arm where the radioactive tracer will be injected. A small amount of the radioactive tracer is then injected. You will lie on your back on a table and a large scanning camera will be positioned closely above or below you. After the radioactive tracer is injected, the camera will scan for radiation released by the tracer and produce pictures as the tracer passes through your veins.

You need to lie very still during each scan to avoid blurring the pictures. The camera does not produce any radiation, so you are not exposed to any additional radiation while the scan is being done.

The vein scan takes about 30 to 60 minutes.