Ecografía vascular

Vascular ultrasound — often called a duplex study — images the blood vessels outside the heart. It combines two things at once: a picture of the vessel wall, and a Doppler measurement of the speed and direction of blood moving through it. Together they show not just where a vessel is narrowed but how much that narrowing is actually affecting flow.

There is no radiation, no dye and no needles, which is why it is the first-line test for most vascular questions and the standard way to follow a known problem over time.

Carotid ultrasound examines the arteries in the neck that supply the brain. It is used after a stroke or TIA, when a bruit is heard in the neck, or to follow known narrowing — and the degree of stenosis it measures is what determines whether a carotid procedure is warranted.

Arterial duplex of the legs locates blockages in the arteries supplying the limbs, usually after an abnormal ankle-brachial index, and maps them before any planned intervention.

Venous duplex looks for deep vein thrombosis in someone with a swollen, painful leg, and is the test used to diagnose or exclude a clot. A venous reflux study asks a different question: whether the valves in the leg veins are failing and allowing blood to flow backward, which is the underlying cause of varicose veins and chronic venous insufficiency. Reflux studies are usually performed standing or on a tilted table, because gravity is what provokes the finding.

Abdominal aortic ultrasound measures the diameter of the aorta to screen for or monitor an aneurysm.

Bypass graft and stent surveillance re-checks a previous repair at intervals to catch a narrowing before it closes.

Most studies take 30 to 60 minutes depending on how much territory is being covered. You lie on an exam table, warm gel is applied, and a sonographer moves the probe firmly along the course of the vessel. You will hear pulsing and whooshing sounds from the Doppler — that is the blood flow being measured, and it is expected. For a leg study you may be asked to change position or stand.

Preparation is minimal for most studies. An abdominal aortic or mesenteric study usually requires fasting for 8 to 12 hours, since bowel gas obscures the view. Neck, leg and vein studies generally require nothing at all. Wear clothing that is easy to move out of the way.

A physician reviews the recorded images and velocity measurements after the study. Because the numbers are compared against your previous studies when you have them, surveillance ultrasounds are most useful when performed on the schedule your vascular specialist sets.