Venous ultrasound provides pictures of the veins throughout the body. A Doppler ultrasound study may be part of a venous ultrasound examination.
For most ultrasound exams, the patient is positioned lying face-up on an examination table that can be tilted or moved.
A clear water-based gel is applied to the area of the body being studied to help the transducer make secure contact with the body and eliminate air pockets between the transducer and the skin. The sonographer (ultrasound technologist) or radiologist then presses the transducer firmly against the skin and sweeps it over the area of interest.
Doppler sonography is performed using the same transducer.
This ultrasound examination is usually completed within 15 minutes.
The most common reason for a venous ultrasound exam is to search for blood clots, especially in the veins of the leg. This condition is often referred to as deep vein thrombosis or DVT. These clots may break off and pass into the lungs, where they can cause a dangerous condition called pulmonary embolism. If found in time, there are treatments that can prevent this from happening.
A venous ultrasound study is also performed to:
- determine the cause of long-standing leg swelling. In people with a common condition called varicose veins, the valves that keep blood flowing back to the heart in the right direction may be damaged, and venous ultrasound can help the radiologist decide how best to deal with this condition.
- map out the veins in the leg or arm so that pieces of vein may be removed and used to bypass a narrowed or blocked blood vessel. An example is using pieces of vein from the leg to surgically bypass narrowed heart (coronary) arteries.
- examine a blood vessel graft used for dialysis if it is not working as expected; for example, the graft may be narrowed or blocked.
Doppler ultrasound images can help the physician to see and evaluate:
- blockages to blood flow (such as clots).
- narrowing of vessels (which may be caused by plaque).
- tumors and congenital malformation.
- Venous ultrasound helps to detect blood clots in the veins of the legs before they become dislodged and pass to the lungs. It can also show the movement of blood within blood vessels.
- Compared to venography, which requires injecting contrast material into a vein, venous ultrasound is accurate for detecting blood clots in the veins of the thigh up to the knee. In the calf, because the veins become very small, ultrasound is less accurate. However, potentially dangerous venous clots are lodged in the larger veins.
What are the limitations of Venous Ultrasound Imaging?
Veins lying deep beneath the skin, especially small veins in the calf, may be hard to see.