Definition & Overview
Ultrasound scanning is a diagnostic test that uses high-frequency sound waves to produce images. It involves a small transducer (a probe that releases and receives the sound) and ultrasound gel that is applied directly onto the skin. The movement of the transducer along the skin produces the images as they are relayed to the computer.
One technique, the Doppler ultrasound, allows the doctor to see and evaluate blood flow through the arteries and veins in the abdomen, arms, legs, neck and brain and within the body’s organs. The venous Doppler exam is a more specific procedure utilizing the power of the Doppler ultrasound technique to focus on the large veins in the legs (leg venous Doppler) or arms (arm venous Doppler).
The Venous Doppler exam shows any blockage in the veins, usually a blood clot (or thrombus formation) that hinders blood circulation.
Who Should Undergo and Expected Results
The legs have two sets of veins - the superficial veins underneath the surface of the skin and the deep veins underneath the muscles. These veins are responsible for pushing the blood toward the heart and prevent it from flowing back down. The leg venous Doppler test aims to evaluate three possible causes that prevent normal blood circulation.
Superficial thrombophlebitis is an inflammation of a vein caused by a blood clot that usually forms in the superficial veins after an injury or in old varicose veins. In some cases, it also occurs after having an intravenous line (IV) or catheter. People who are at risk usually get this condition from sitting or staying still for a prolonged period and using birth control pills. Those who have varicose veins, are pregnant and have disorders that involve increased blood clotting are also at risk. The most common symptom of the condition is inflammation along the vein, limb pain or hardening of the vein.
Deep venous thrombosis (DVT) is the condition when a blood clot forms within the deep veins in the legs and sometimes in the arms. A blood clot forms when the flow of blood through the veins slows down. There are many instances that can change the flow of blood, such as prolonged bed rest or sitting in one position too long (like when traveling on a plane), family history of blood clots, fractures in the pelvis or legs, pregnancy and giving birth, obesity, and recent surgery. People who have DVT almost always experience leg pain and swelling.
Venous insufficiency is the condition when the veins are weakened and the valves in the deep leg veins are unable to keep blood flowing back toward the heart. The veins then become filled with blood causing heaviness, cramping and pain in the legs especially when standing, varicose veins and redness of the legs and ankles.
Normal test results show that the veins do not indicate any narrowing, blood clots and the arteries have normal blood flow. However, abnormal results can indicate a blockage, a blood clot, a narrowing or widening of an artery, or a venous occlusion (closing of vein).
How Does the Procedure Work?
A leg venous Doppler exam is performed in a hospital’s ultrasound or radiology department, at a doctor’s office or a peripheral vascular lab.
There are no preparations needed for this exam. However, smokers may be asked to stop smoking at least a day prior to the procedure as smoking constricts the blood vessels, affect the test results.
The following are to be expected during the procedure:
Patients are asked to change into a hospital gown for ease and convenience before lying on an examination table or bed.
The technician or doctor will apply a clear, water-soluble gel on the skin or on the transducer to establish secure contact with the body to better transmit the sound waves to and from the area being checked. The technician will then move the transducer along the skin in various locations of interest for a better look at the area.
For leg arteries, the doctor will look for the narrowing of blood vessels. He may apply blood pressure cuffs to different positions on the leg, like the thigh, calf and ankle to compare the blood pressure from the different parts of the leg being examined.
Once the imaging process is finished, the gel will be wiped off.
The whole process will normally take an hour and patient can immediately resume their regular daily activities.
The results will be forwarded to the diagnosing doctor within 2 to 3 days during which time the patient is expected to have to follow-up with the doctor. If there are some anomalies with the test or there were suspicious findings, more tests and monitoring may be required.
Possible Risks and Complications
The leg venous Doppler exam is a painless, non-invasive procedure. There are no risks although there may be a bit of discomfort when the transducer runs over an area that is sore or tender. The procedure may also result in pulse-like sounds when the transducer runs over the arteries. These sounds change in pitch to indicate the blood flowing in the veins.
- Fowler GC, Reddy B. Noninvasive Venous and Arterial Studies of the Lower Extremities. In: Pfenninger JL, Fowler GC, eds. Pfenninger & Fowler's Procedures for Primary Care. 3rd ed. Philadelphia, PA: Elsevier Mosby; 2011:chap 88.