Doppler ultrasound

A medical Doppler study is a noninvasive test that can be used to evaluate blood flow and pressure by bouncing high-frequency sound waves (ultrasound) off red blood cells.

The Doppler effect is a change in the frequency of sound waves caused by moving objects. A Doppler study can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). This test may be done as an alternative to more invasive procedures such as arteriography and venography, which involve injecting dye into the blood vessel to provide X-ray images.

A Doppler study may help diagnose many conditions, including:

• Blood clots
• Incompetent valves in your leg veins, which cause fluid to accumulate (venous insufficiency)
• Heart valve defects and congenital heart disease
• A blocked artery (arterial occlusion)
• Narrowing (stenosis) of an artery

This test may also help your doctor evaluate an injury to the arteries or help monitor arterial reconstruction and bypass grafts.