A Doppler ultrasound is an imaging test that uses sound waves to show blood moving through blood vessels. A regular ultrasound also uses sound waves to create images of structures inside the body, but it can’t show blood flow.
Doppler ultrasound works by measuring sound waves that are reflected from moving objects, such as red blood cells. This is known as the Doppler effect.
There are different types of Doppler ultrasound tests. They include:
- Color Doppler. This type of Doppler uses a computer to change sound waves into different colors. These colors show the speed and direction of blood flow in real time.
- Power Doppler, a newer type of color Doppler. It can provide more detail of blood flow than standard color Doppler. But it cannot show the direction of blood flow, which can be important in some cases.
- Spectral Doppler. This test shows blood flow information on a graph, rather than color pictures. It can help show how much of a blood vessel is blocked.
- Duplex Doppler. This test uses standard ultrasound to take images of blood vessels and organs. Then a computer turns the images into a graph, as in spectral Doppler.
- Continuous wave Doppler. In this test, sound waves are sent and received continuously. It allows for more accurate measurement of blood that flows at faster speeds.
Other names: Doppler ultrasonography
What is it used for?
Doppler ultrasound tests are used to help health care providers find out if you have a condition that is reducing or blocking your blood flow. It may also be used to help diagnose certain heart diseases. The test is most often used to:
- Check heart function. It is often done along with an electrocardiogram, a test that measures electrical signals in the heart.
- Look for blockages in blood flow. Blocked blood flow in the legs can cause a condition called deep vein thrombosis (DVT).
- Check for blood vessel damage and for defects in the structure of the heart.
- Look for narrowing of blood vessels. Narrowed arteries in arms and legs can mean you have condition called peripheral arterial disease (PAD). Narrowing of arteries in the neck can mean you have a condition called carotid artery stenosis.
- Monitor blood flow after surgery.
- Check for normal blood flow in a pregnant woman and her unborn baby.
Why do I need a Doppler ultrasound?
You may need a Doppler ultrasound if you have symptoms of reduced blood flow or a heart disease. Symptoms vary depending on the condition causing the problem. Some common blood flow conditions and symptoms are below.
Symptoms of peripheral arterial disease (PAD) include:
- Numbness or weakness in your legs
- Painful cramping in your hips or leg muscles when walking or climbing stairs
- Cold feeling in your lower leg or foot
- Change in color and/or shiny skin on your leg
Symptoms of heart problems include:
- Shortness of breath
- Swelling in your legs, feet, and/or abdomen
You may also need a Doppler ultrasound if you:
- Have had a stroke. After a stroke, your health care provider may order a special kind of Doppler test, called transcranial Doppler, to check blood flow to the brain.
- Had an injury to your blood vessels.
- Are being treated for a blood flow disorder.
- Are pregnant and your provider thinks you or your unborn baby might have a blood flow problem. Your provider may suspect a problem if your unborn baby is smaller than it should be at this stage of pregnancy or if you have certain health problems. These include sickle cell disease or preeclampsia, a type of high blood pressure that affects pregnant women.
What happens during a Doppler ultrasound?
A Doppler ultrasound usually includes the following steps:
- You will lie a table, exposing the area of your body that’s being tested.
- A health care provider will spread a special gel on the skin over that area.
- The provider will move a wand-like device, called a transducer, over the area.
- The device sends sound waves into your body.
- The movement of blood cells causes a change in the pitch of the sound waves. You may hear swishing or pulse-like sounds during the procedure.
- The waves are recorded and turned into images or graphs on a monitor.
- After the test is over, the provider will wipe the gel off your body.
- The test takes about 30-60 minutes to complete.
Will I need to do anything to prepare for the test?
To prepare for a Doppler ultrasound, you may need to:
- Remove clothing and jewelry from the area of the body that is getting tested.
- Avoid cigarettes and other products that have nicotine for up to two hours before your test. Nicotine causes blood vessels to narrow, which can affect your results.
- For certain types of Doppler tests, you may be asked to fast (not eat or drink) for several hours before the test.
Your health care provider will let you know if you need to do anything to prepare for your test.
Are there any risks to the test?
There are no known risks to having a Doppler ultrasound. It is also considered safe during pregnancy.
What do the results mean?
If your results were not normal, it may mean you have:
- A blockage or clot in an artery
- Narrowed blood vessels
- Abnormal blood flow
- An aneurysm, a balloon-like bulge in the arteries. It causes the arteries to become stretched and thin. If the wall becomes too thin, the artery can rupture, causing life-threatening bleeding.
Results may also show if there is abnormal blood flow in an unborn baby.
The meaning of your results will depend what area of the body was being tested. If you have questions about your results, talk to your health care provider.
Courtesy of MedlinePlus from the National Library of Medicine.