What is it?

An ultrasound uses reflected sound waves to produce a picture of organs and blood vessels. The sound waves create a picture on a video screen.

Doppler ultrasound is a special kind of ultrasound. It can detect movement of blood through arteries and veins.

Some ultrasound tests are called "duplex." Duplex means "two parts." A duplex ultrasound combines the Doppler ultrasound with the more common ultrasound. The combination can help the doctor see more clearly what's going on.

There are no risks linked to an ultrasound test, and it is safe for pregnant women. It won't harm the baby (fetus).

Why is this test done?

You might have a Doppler ultrasound to:

• Look for reduced blood flow in major neck arteries. Low blood flow in these arteries can cause a stroke.
• Find a blood clot in leg veins, which could be a deep vein thrombosis.
• Check blood flow in a fetus to check the health of the fetus.
• Find a blockage or a narrowing in the arteries that go to the kidneys.

How do you prepare for the test?

Depending on what the test is for, you may be asked not to eat or drink after midnight before the test. Or you may be asked to drink water right before the test so that your bladder is full.

How is the test done?

The doctor or ultrasound technologist will have you lie on your back, side, or stomach, depending on which part of your body is being examined.

• A gel will be applied to your skin. This helps the passage of sound waves.
• A hand-held device called a transducer will be moved along your skin.
• You'll need to stay still during the test.

How long does the test take?

The test will take 30 to 60 minutes.

What happens after the test?

• The scans from the test will be read within a short time, in case a repeat test is needed.
• You will probably be able to go home as soon as the test has been read.
• You can go back to your usual activities right away.