Test Overview

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.

How It Feels

You may feel nothing at all from the needle puncture when the tracer is injected, or you may feel a brief sting or pinch as the needle goes through the skin. Otherwise, a vein scan is usually painless. You may find it difficult to remain still during the scan. Ask for a pillow or blanket to make yourself as comfortable as possible before the scan begins.

Risks

Allergic reactions to the radioactive tracer are rare. Most of the tracer will be eliminated from your body (through your urine or stool) within a day, so be sure to promptly flush the toilet and thoroughly wash your hands with soap and water. The amount of radiation is so small that it is not a risk for people to come in contact with you following the test.

Occasionally, some soreness or swelling may develop at the injection site. These symptoms can usually be relieved by applying moist, warm compresses to your arm.

There is always a slight risk of damage to cells or tissue from being exposed to any radiation, including the low level of radiation released by the radioactive tracer used for this test.

Results

A vein scan is a nuclear scanning test to detect blood clots in the deep veins of the legs (called deep vein thrombosis or DVT). The results of a vein scan are usually available in 1 day.

What Affects the Test

Factors that can interfere with your test and the accuracy of the results include:

• Pregnancy. A vein scan is not usually done during pregnancy because the radiation could damage the developing baby (fetus).
• Barium and bismuth. If a vein scan is needed, it should be done before any tests that use barium (such as a barium enema).
• The inability to remain still during the test.

What To Think About

• Other tests, such as Doppler ultrasound and venography, are often used instead of a vein scan to detect blood clots. The Doppler ultrasound provides quick and accurate results without the use of radiation, but unlike a vein scan, it may be less accurate at distinguishing an old clot from a newly forming one. However, if the results of those tests are not clear, a vein scan may be done to confirm the location of a newly forming blood clot, especially for a person who has recurring blood clot problems. For more information, see the medical tests Doppler Ultrasound and Venogram.
• A vein scan may be done for a person who cannot undergo venography because of a history of severe allergy to contrast material.