Doppler ultrasound is a technique used to measure the flow of blood through your arteries and blood vessels—usually those in your extremities. Vascular flow studies, also known as blood flow studies, can detect abnormal flow within a 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.
This risk-free and pain-free procedure requires little preparation and can provide your doctor with valuable information about your blood pressure and any arterial blockages you may have.
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. This may be due to an arterial blockage, a blood clot inside a blood vessel or bypass graft, or an injury to a blood vessel.
The Doppler ultrasound exam may be ordered if you have (or if your doctor thinks you may have):
- deep vein thrombosis (a blood clot in a vein deep inside your body)
- superficial thrombophlebitis (inflammation due to a blood clot in a vein just below the skin’s surface)
- arteriosclerosis of the extremities (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 obstructed)
- vascular tumors in your arms or legs
A Doppler ultrasound will be able to measure the blood flow through the arteries or veins in question. The test can show how much blood flows through your arteries with each heartbeat as well as the blood pressure within your arteries.
Generally, no preparation is required for this test. However, if you are a smoker, your physician may ask you to stop smoking for several hours before the test because smoking causes your blood vessels to constrict.
This is a noninvasive, painless procedure that will not expose you to harmful radiation. There are no risks associated with this test, and most people feel little or no discomfort during or after the procedure.
The test is usually performed in the radiology department of a hospital, doctor’s office, or peripheral vascular lab. The procedure can vary slightly, depending on the doctor, technician, and hospital. In general, you can expect the following:
- You will need to remove clothing, jewelry, and any other objects from the area to be studied. You may be asked to wear a hospital gown. There is no need to remove your glasses, contact lenses, dentures, or hearing aids.
- The procedure will take place with you lying on an examination table or bed.
- To examine your veins, a water-soluble gel will be placed on a handheld device called a transducer (similar to a microphone), which directs high-frequency sound waves into the arteries or veins being studied.
- To examine your arteries, blood pressure cuffs may be placed around different parts of your body, including your thigh, calf, ankle, and various points along your 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 your blood vessels and send the information to a monitor to be processed and recorded. The transducer will be moved to different areas for comparison. You may hear a "whooshing" sound as blood flow is detected
Doppler Ultrasound Exam of Leg Arteries
When examining your leg arteries, your doctor will look for narrowing of the blood vessels that may cause you pain when walking or resting, skin discoloration, or ulcers of the foot, ankle, heel, or toe.
During the procedure, blood pressure cuffs will be placed in several positions on your leg. This is to help compare the blood pressure in different parts of your leg. The cuffs will generally be applied to the thigh, calf, and ankle. Your blood pressure will also be taken on the arm on the same side of your body as the leg being studied.
Your exam will be completed in about an hour. Depending on your signs and symptoms, you may be asked to perform some mild exercises after the exam.
After the Procedure
For most people, there are no special instructions following the procedure. Unless advised differently by your doctor, you may resume your usual activities right away.
Normal test results indicate that you have no narrowing or blockages in your arteries and that the blood pressure in your arteries is normal. Abnormal blood flow patterns, including narrowing or closure of the arteries, can indicate:
- blockage in the arteries (sometimes due to cholesterol buildup)
- blood clot(s) in a vein or artery
- poor circulation (can be related to blood vessel damage from chronic conditions, such as diabetes)
- venous occlusion (closing of a vein)
- spastic arterial disease
- blockage or clots in an artificial bypass graft
There are some factors that may compromise the results and require a repeat of the test or other additional testing. These include:
- smoking less than one hour before the test (smoking causes your blood vessels to constrict)
- severe obesity
- cardiac dysrhythmias/arrhythmias (irregular heart rhythms)
- cardiovascular disease
The test results will be sent to your doctor. If abnormalities are found, your doctor will discuss any additional tests or treatments with you.