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Home > Patients & Visitors > Health Library > Doppler Ultrasound
ultrasound test uses reflected sound waves to see how
blood flows through a blood vessel. It helps doctors assess the blood flow
through major arteries and veins, such as those of the arms, legs, and neck. It can show
blocked or reduced flow of blood through narrow areas in the major arteries of the
neck. This problem could cause a
stroke. The test also can find blood clots in leg veins
(deep vein thrombosis, or DVT) that could break loose
and block blood flow to the lungs. This problem is called a pulmonary embolism. During pregnancy, Doppler ultrasound may be
used to look at blood flow in an unborn baby to check
the baby's health.
During Doppler ultrasound, a handheld
device is passed lightly over the skin above a blood vessel.
The device is called a transducer. It sends and receives sound waves that are amplified through a
microphone. The sound waves bounce off solid objects, including blood cells.
The movement of blood cells causes a change in the pitch of the reflected sound
waves. This is called the Doppler effect. If there is no blood flow, the pitch does
Information from the reflected sound waves can be used to make graphs or pictures that show the flow of blood through
the blood vessels. These graphs or pictures can be saved and reviewed later.
The three basic types of Doppler ultrasound
Doppler ultrasound is done to:
A transcranial Doppler (TCD) ultrasound may be used in
children with sickle cell disease. The test can check for the risk of stroke.
For 30 minutes to 2 hours
before the test, you may need to stop using products
that contain nicotine. This includes cigarettes and chewing tobacco. Nicotine causes blood vessels to narrow, which may give false
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 jewelry 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.
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.
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
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.
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
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 maneuver. The examiner may do this maneuver 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 maneuver.
It is done to check blood flow toward your heart.
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 maneuver. It usually causes a
sudden change in blood flow through the veins.
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.
For this type of
ultrasound, the transducer is passed lightly over the skin at the base or side
of your skull.
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.
Having a Doppler ultrasound test doesn't normally cause discomfort. The gel may feel cold when it is put on
your skin unless it is warmed first. If your blood pressure
is taken during the test, you will feel pressure when the blood pressure cuff
There are no known risks linked with a
Doppler ultrasound test. This test will not harm an unborn baby (fetus).
ultrasound test uses reflected sound waves to see how
blood flows through a blood vessel.
The test does not show
significant narrowing or other problems in any of the arteries.
There is no sign of a clot
in any of the veins examined. The size and position of veins are
Normal blood flow is found in
the blood vessels that supply oxygen and nutrients to a
For continuous wave Doppler or
duplex Doppler, differences in blood flow between the right and left sides of
the body may be heard. At the exact spot where an artery is blocked or
narrowed, the sound may be high-pitched or turbulent. Blockage (such as from a
blood clot), an
aneurysm, or narrowing of a blood vessel may be
found. The speed of blood flow may be compared to standard values to find
out how blocked or narrow the blood vessel is.
A duplex Doppler ultrasound
graph may show blood flow that isn't normal. This is a sign of a blocked or narrowed blood
A color Doppler image may show
a blocked or narrowed blood vessel or an aneurysm.
In the veins, a blood clot may
be present if blood flow does not change in response to breathing or does not
increase after either a compression maneuver or
Valsalva maneuver. Incomplete blockage of a vein by a
blood clot may be seen on color Doppler or during a compression
Abnormal veins, such as
varicose veins, are seen.
There is an abnormal increase or decrease in blood flow through the
vessels that supply oxygen and nutrients to a fetus.
You may not be able to
have the test, or the results may not be helpful, if:
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Roman AS (2013). Late pregnancy complications. In AH DeCherney et al., eds., Current Diagnosis and Treatment Obstetrics & Gynecology, 11th ed., pp. 250–266. New York: McGraw-Hill.
ByHealthwise StaffPrimary Medical ReviewerKathleen Romito, MD - Family MedicineSpecialist Medical ReviewerHoward Schaff, MD - Diagnostic Radiology
Current as ofAugust 21, 2015
Current as of:
August 21, 2015
Kathleen Romito, MD - Family Medicine & Howard Schaff, MD - Diagnostic Radiology
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