A Doppler ultrasound is a test that uses high frequency sound waves (ultrasound) to measure the amount of blood flow through your arteries and veins, usually those that supply blood to your arms and legs.
Vascular flow studies, also known as blood flow studies, can detect abnormal flow within an artery or blood vessel. This can help to diagnose and treat a variety of conditions, including blood clots and poor circulation. A Doppler ultrasound can be used as part of a blood flow study.
A Doppler ultrasound is a risk-free and pain-free procedure that requires little preparation. The test provides your doctor with important information about the flow of blood through your major arteries and veins. It can also reveal blocked or reduced blood flow through narrowed areas in the arteries, which could eventually lead to a stroke.
You doctor may suggest a Doppler ultrasound exam if you show signs of decreased blood flow in the arteries or veins of your legs, arms, or neck. A reduced amount of blood flow may be due to a blockage in the artery, a blood clot inside a blood vessel, or an injury to a blood vessel.
The Doppler ultrasound exam may be ordered if you show signs of:
- deep vein thrombosis, a condition that occurs when a blood clot forms in a vein deep inside your body (usually in the leg or hip regions)
- superficial thrombophlebitis, an inflammation of the veins due to a blood clot in a vein just below the skin's surface
- arteriosclerosis, a narrowing and hardening of the arteries that supply blood to the legs and feet
- thromboangiitis obliterans, a rare disease in which the blood vessels of the hands and feet become inflamed and swollen
- vascular tumors in your arms or legs
A Doppler ultrasound can help determine the blood pressure within your arteries and show how much blood is currently flowing through your arteries and veins.
In general, there’s no preparation required for this test. However, if you’re a smoker, your doctor may ask you to stop smoking for several hours before the test. Smoking causes your blood vessels to narrow, which can affect the results of your test.
A Doppler ultrasound is a noninvasive, painless procedure that doesn’t expose you to harmful radiation. There are no risks associated with this test, and most people feel little to no discomfort during the procedure.
The test is usually performed in the radiology department of a hospital, doctor's office, or peripheral vascular laboratory. The procedure can vary slightly, but in general, you can expect the following:
- You will need to remove clothing, jewelry, and any other objects in the area that will be studied. However, there’s no need to remove your glasses, contact lenses, dentures, or hearing aids. You may be asked to wear a hospital gown.
- Before the procedure, you’ll be instructed to lie down on an examination table or bed.
- Your doctor will then place a water-soluble gel on a handheld device called a transducer, which directs high-frequency sound waves into the arteries or veins being studied.
- To examine your arteries, blood pressure cuffs may be placed around various areas of your body. The cuffs will generally be applied to your thigh, calf, ankle, or various points along your arm. They help compare the blood pressure in different parts of your leg or arm.
- Images are created as the transducer is pressed against your skin and moved along your arm or leg. The transducer sends sound waves through your skin and other body tissues to the blood vessels. The sound waves echo off of your blood vessels and send the information to a computer to be processed and recorded. The computer will produce graphs or pictures that show the flow of the blood through the arteries and veins. The transducer will be moved to different areas for comparison. You may hear a "whooshing" sound as blood flow is detected.
When examining your leg arteries and veins, your doctor will look for narrowing of the blood vessels. This condition may cause skin discoloration, pain when you walk or rest, and ulcers on the foot or ankle.
The test will be completed in about an hour. Depending on your signs and symptoms, you may be asked to perform some mild exercises after the procedure.
After the Procedure
For most people, there are no special instructions following a Doppler ultrasound. You may resume your usual activities right away, unless your doctor tells you otherwise.
Normal test results indicate that you have no narrowing or blockages in your arteries. It also means that the blood pressure in your arteries is normal. Abnormal blood flow patterns, including narrowing or closing of the arteries, can indicate:
- blockage in the arteries, which may be due to a buildup of cholesterol
- blood clot(s) in a vein or artery
- poor circulation, which can be caused by damaged blood vessels
- venous occlusion, or closing of a vein
- spastic arterial disease, a condition in which the arteries contract due to stress or exposure to cold weather
- blockage or clots in an artificial bypass graft
There are some factors that may compromise the results, which means the test will need to be done again. These factors include:
- smoking less than one hour before the test
- severe obesity
- cardiac dysrhythmias and arrhythmias, or irregular heart rhythms
- cardiovascular disease
The test results will be sent to your doctor. If any abnormalities are found, your doctor will explain your results in more detail and inform you about any additional tests or treatments that may need to be done.