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How does duplex ultrasound work?

This question was asked in Akron, Ohio and has 6 answer(s) as of 08/13/2013.
How does an ultrasound check for venous insufficiency? What do you find out when you do a venous reflux test and how does that help in solving venous problems?


Doctors Answers (6)

An ultrasound examination can visualize the anatomy in the leg by visualizing the changes in density of the various structures below the skin including the veins. A Duplex ultrasound can also measure both the movement and direction of blood flow below the skin. It can distinguish between the pulsating flow of the arteries and the slow flow in the veins. Normally, there are valves in the larger veins that act to prevent backward or reverse flow (reflux), but if the valves are not functioning correctly, then reflux can be seen and measured. Duplex ultrasound is important to determine both the anatomy and function of the veins, and if there is a poorly functioning vein, it will determine the extent of the problem as the first step in planning treatment of larger varicose veins, leg swelling, skin changes over the shin area, spontaneous vein bleeding, venous ulceration, and chronic sore legs.

The ultrasound will determine if the blood in your veins is flowing backwards (or refluxing). If this is happening we know the vein is causing a circulation problem and needs to be treated to treat your disease.

The duplex ultrasound exam serves many functions. We use imaging to map the location of the major veins of the extremities and to identify abnormal sizes and other structural abnormalities of the veins. We look for evidence of recent or old clots in the veins and we also look for evidence of any obstruction of venous flow in the legs or hints of obstruction of venous flow in the pelvic veins. Normal venous flow in the legs is toward the heart and from superficial veins in the fatty tissues toward the deep veins in the muscle of the legs. Abnormal flow away from the heart or from the deep veins to the superficial veins usually occurs because some of the one-way valves in the veins fail. This allows reversal of the normal flow direction which results in high pressures building up in the superficial veins of the skin and fatty tissues. This reversal of flow is called venous insufficiency and the reversed flow is called venous reflux. The ultrasound machine provides images and measures the direction and the velocity of flow within the blood vessels. Veins which are major sources of reflux need to be treated to reduce the downward (reversed) flow of venous blood when there is significant pain, tenderness, swelling, or varicose vein formation due to the reflux.

Duplex ultrasound shows images of vein size and valve function. Color Doppler shows flow of blood within the veins. This allows us to determine venous health and recommend a treatment plan. Ultrasound does not treat the vein.

The ultrasound provides critical information about the size of the vein and the degree of reflux, if any. Reflux represents the degree to which blood runs backwards, which represents the severity of valvular insufficiency. It also evaluates the deep veins, which is also critical to understand.

A venous duplex ultrasound is a non invasive test to examine vein valve function, direction of blood flow, speed of blood flow, as well as vein size on an imaging screen. During the test, the patient's leg is gently compressed to see how long the blood flows and its direction. If the venous blood flows significantly " backwards " away from the heart it means that the vein may need treatment.

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