Tests for Veins - Duplex Ultrasound of Abnormal Veins

Click here to see a short video clip of an ultrasound scan »

In this video, again the head ("up") is on the left and the foot ("down") is on the right. Once again the examiner squeezes the calf muscle to make the blood flow in the veins.

This video shows good flow (blue colour) in the veins on squeezing the calf. However in this patient, the valves are not working as the patients has venous reflux (varicose veins).

As the calf is released, a lot of red flow is seen, showing that the valves are not working and a large volume of blood that should be going back to the heart is in fact flowing back down the leg.

Incompetent Veins - and failing valves: (see How Veins Works section)

When the valves in a vein do not work, they are called "incompetent".

The colour flow on the Duplex Ultrasound above can be compared with the arrows representing flow on the animation on the right - which shows what happens in the veins when the valves fail and blood refluxes.

The muscle squeezes the vein and the blood is forced up and out of the vein, as in normal veins.

However, when the pressure eases and the veins open up, the blood is allowed to fall back down the leg as the valves are not able to prevent it. This is called venous "reflux".

Venous reflux is the major cause of most venous diseases and is almost always the cause of varicose veins.