How It Is Done

This test is done by a doctor who is an expert in imaging tests (radiologist). Or it may be done by an ultrasound technologist (sonographer) who works with a radiologist. It is done in an ultrasound room in a hospital or doctor's office.

You will need to remove any jewellery that might affect the Doppler ultrasound scan. You may need to take off all or most of your clothes, depending on which part of the body is being examined. You may be allowed to keep on your underwear if it does not affect the test. You will be given a cloth or paper covering to use during the test.

• For abdominal scans, you will lie on your back.
• For chest scans, you will lie on your back with your neck slightly extended.
• For head and neck scans, your head may be turned to one side.
• For an arm or leg scan, your head will be slightly raised. The exposed arm or leg will be turned slightly outward. Sometimes for a leg scan, you may be asked to lie on your stomach.
• During pregnancy, you will lie on your back or on your left side with your belly exposed.

Gel is applied to the skin to help the sound waves pass through. The transducer is placed in the gel and moved along the skin. You need to lie very still during the test. You may hear sounds from the flow of blood through the blood vessels.

The test usually takes 30 to 60 minutes.

Arteries in the arms and legs

This test is often done on both arms or both legs. Even if the suspected blood flow problem is in only one limb, both may be tested to compare them. If your arms are being tested, they will be tested first while you lie down. Then they'll be tested again while you sit.

Depending on which blood vessels are being tested, a blood pressure cuff may be wrapped around one or both limbs. It allows your blood pressure to be taken at several different places. When the legs are tested, a blood pressure cuff may be wrapped first around the calf and then around the thigh. The test may be done at several places on your leg. When the arms are tested, the pressure cuff may be wrapped first around the forearm and then around the upper arm.

Testing may be done before and after exercise, if you are healthy enough.

Veins in the arms and legs

For this test, you will be asked to lie down and breathe normally. You must lie very still. Any changes in blood flow that are affected by how you breathe are noted.

The test may be repeated while the examiner presses on the veins close to the surface of your skin. This helps to find a clot in the vein. It's called a compression manoeuvre. The examiner may do this manoeuvre with your legs or arms in different positions. This is to make sure that the blood supply is not blocked in these positions. He or she may also squeeze your calf or forearm to help blood move more quickly through the veins. This is called an augmentation manoeuvre. It is done to check blood flow toward your heart.

While your legs are being tested, you may also be asked to try to breathe out strongly with your nose pinched and your mouth closed. This is called a Valsalva manoeuvre. It usually causes a sudden change in blood flow through the veins.

Arteries in the neck

You will be asked to lie down with a pillow under your head for support. The test is done on both sides of your neck. Then the results are compared to standard values to find out how much the arteries are blocked or narrowed.

Transcranial ultrasound

For this type of ultrasound, the transducer is passed lightly over the skin at the base or side of your skull.

During pregnancy

The transducer is moved back and forth on your belly until the doctor finds the blood vessel that needs to be studied. After the doctor has found the blood vessel, it may take some time to assess the blood flow.