What Is a Duplex Ultrasound?

Today's quick video is about duplex ultrasound, one of the most important tests we use in vascular surgery. You may hear doctors say "we'll arrange a duplex scan", especially for varicose veins, leg swelling, blocked arteries or possible clots. So what does duplex ultrasound actually mean?

Ultrasound uses high-frequency sound waves. These sound waves reflect off tissues and return to the probe, allowing the machine to create an image. So ultrasound gives us the picture. Doppler also uses sound waves, but it looks at movement, especially blood flowing and moving through a vessel. The machine converts that movement into a signal we can hear or measure. So Doppler tells us about flow.

Duplex means we are using both together: the ultrasound image plus Doppler flow information. That matters because in vascular surgery I need to know where the blood is flowing, which direction it's flowing in, and whether there's a narrowing, blockage, reflux or a clot.

In our practice, we have our own vascular laboratory and a dedicated vascular sonographer who focuses on vascular scans every day. So, in simple terms, ultrasound gives us the image, Doppler gives us the flow and duplex gives us both.