What is a duplex scan?

This article is for people who have been advised to have a duplex ultrasound scan as part of the consultation process for varicose vein or spider vein treatment. It explains why the procedure is necessary and what it involves.

What is a duplex scan?

A duplex ultrasound scan is a non-invasive procedure that uses high-frequency sound waves (ultrasound) to examine the structure of your leg veins and the speed of blood flow within them.

How does it work?

A duplex scan combines two ultrasound techniques: B-mode (also known as greyscale) and Doppler (named after the Austrian physicist Christian Doppler).

B-Mode Ultrasound

B-mode is the type of ultrasound that most people associate with pregnancy scans. It produces a black and white image of structures within the body. In venous investigations, the B-mode technology within a duplex ultrasound shows the location of veins within the leg.

Doppler Ultrasound

A Doppler scan adds information to the B-mode image. It bounces ultrasound off circulating red blood cells to show the direction and rate of blood flow within veins.

Why do I need a duplex scan before leg vein removal?

The National Institute for Health and Care Excellence (NICE) recommends using a duplex scan to “confirm the diagnosis of varicose veins and the extent of truncal reflux, and to plan treatment for people with suspected primary or recurrent varicose veins”. The procedure allows your consultant to locate any damaged valves that may be causing visible or hidden varicose veins and identify the most suitable treatment options.

Why do I need a duplex scan before spider vein treatment?

In approximately 80 – 90% of people with spider veins (also known as thread veins), their condition is caused by hidden varicose veins and in 40% of people, there will be a problem with major veins (truncal venous reflux). Finding and treating these conditions makes spider vein treatment far more effective.

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What does the procedure involve?

Your consultant first applies a gel to the skin at the point of examination. The ultrasound probe is then placed on the gel, and the machine sends ultrasound into the body through the probe. The sound waves bounce off any structures within the body and return echoes to the probe. These echoes are transmitted back to the machine and converted into a black and white image on the monitor. You will be standing throughout the procedure, and your consultant will gently squeeze your calf to make blood flow through your leg veins.

Is the scan painful?

No. The gel and probe may feel a little cold initially, but ultrasound does not cause any pain or pose any risks. The procedure does not require an anaesthetic or the use of needles.

How long will it take?

Your consultant will need to assess all of the veins in both of your legs. A full and thorough examination usually takes 10 – 15 minutes.

How do I prepare for it?

You don’t need to do anything to prepare for a duplex scan. You should continue to take your usual medication, and you can eat and drink normally before the test.

Contact us for more information

Premier Veins offers a range of walk-in-walk-out treatments for varicose veins and thread veins. If you would like to talk to us about our treatment packages or book a FREE no-obligation mini-consultation, please contact our friendly reception team who will be happy to help:

Call us: 0121 769 2646

Email us: reception@premierveins.uk

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