Leg Artery Ultrasound (complete, both legs)

What it is

When leg muscles ache after a predictable distance of walking and settle with rest, the suspicion is that the arteries supplying them have narrowed and cannot deliver more blood on demand. An ankle pressure measurement can say that something is restricting flow; it cannot say where. A duplex scan can. Duplex means two things at once: a grey-scale ultrasound picture of the vessel wall, and a Doppler trace of the blood inside it. Blood speeds up as it squeezes through a narrowing, so the sonographer walks the probe along each artery and watches for the point where the velocity jumps — that point is the lesion, and how far the velocity climbs is a measure of how tight it is.

Complete and bilateral describe the extent: the arteries of both legs followed along their course rather than a single segment checked. That is the version ordered when the question is where to intervene, because a surgeon or interventional radiologist needs the whole road map, not one intersection.

Why it is done

• To locate and grade narrowings in the leg arteries in someone with pain on walking, rest pain, cool feet or a sore that will not heal
• To plan a bypass or a catheter-based treatment, by showing which segments are open and which are not
• To follow a graft or a stent afterward and detect narrowing before it closes off
• To assess an artery that has ballooned rather than narrowed, such as an aneurysm behind the knee

What to expect

Preparation is minimal, though you may be asked to fast if the study is extended up into the abdomen. Wear something that comes off easily; you will undress from the waist down and be covered. You lie on a table while the sonographer spreads warm gel and works down each leg, pressing the probe along the line of each artery and holding it still to record measurements. You will hear the Doppler signal out loud — a rhythmic whooshing. It is not painful, though the pressure can be firm over bony areas, and a complete bilateral study takes time because there is a lot of ground to cover. A physician reads the recorded images and measurements afterward.

Questions worth asking

• Is this billed once for both legs, or is each leg a separate charge?
• Would a limited study of one segment answer my doctor's question, and what is the price difference?
• Is there a separate professional fee for the vascular specialist who interprets the study, on top of the fee for performing it?
• Is the vascular lab accredited, and does my insurer require accreditation for the study to be covered?