Duplex ultrasound is a test that is not painful and uses sound waves to create pictures of the veins and arteries. Duplex ultrasound can also evaluate blood flow including amount of blood flow and direction of blood flow.
How is it done?
Duplex ultrasound of the leg veins is performed either standing or on a tilt table with your legs down. Every effort is made to make you feel comfortable and relaxed.
What does the duplex ultrasound show?
When your legs are dependent, there is often no blood flow in the veins in your legs. Blood moves in the veins when the calf muscle is squeezed and therefore compresses the vein and moves the blood. After the blood moves forward, there are a series of one-way valves which close, thereby preventing the backwards flow of blood. When the valves fail, there is added blood flow and pressure in the veins leading to varicose veins.
The examiner saves images showing the size of the vessels and any reversed flow and the length of time of the reversed flow.
The image to the right shows the initial squeeze of the muscle – seen below the line. Then, there is flow above the line for over 4000 msec or 4 seconds. The backwards flow for this duration of time indicates vein valve failure.
Who should perform this examination on me?
Ask if the person performing the examination is certified by the American Registry for Diagnostic Medical Sonography (ARDMS). In addition, for this type of examination, the examiner should be a Registered Vascular Technologist (RVT). Certification is important. Knowing how to perform the examination takes training and experience. Accreditation of the laboratory in vascular testing shows that the training and protocols meet national standards.