What is a doppler ultrasound?
Also known as doppler ultrasonography, the doppler ultrasound is a diagnostic imaging test that uses high-frequency sound waves to show the blood flow through blood vessels in real time. It uses the same technology of a standard ultrasound exam, but applies to it the doppler effect, by having the sound waves bounce off the red blood cells which are moving within the blood vessels.
It is a safe, non-invasive and painless diagnostic procedure which does not emit harmful radiations.
What is a color doppler ultrasound?
A color doppler ultrasound is the same as a doppler ultrasound, but in this case the computer converts the data received into colors, making it easier to see the speed and direction of the blood through the blood vessels.
What is doppler ultrasound used for?
Doppler ultrasound helps evaluating the status of the blood vessels and the cardiocirculatory system. It can be used to:
- Monitor the blood flow to organs and tissues
- Check heart function and heart valves defects (echocardiography)
- Find blockages or narrowing of blood vessels
- Find blood clots
- Post-surgical monitoring of procedures such as bypasses
- Find aneurysms
- Evaluate varicose veins
- Monitor the blood circulation in babies, placenta and uterus in high-risk pregnancies.
What do the colors mean in a doppler ultrasound?
Colors are assigned to the moving objects within the blood vessels such as the red blood cells (RBC). Objects that move towards the probe (transducer) have red color, while objects moving away from it have blue color. The speed of the flow is represented by the shade of red or blue, with lighter color meaning higher speed and darker colors meaning lower speed.
What does the sound mean?
The doppler ultrasound also produces a distinctive sound when monitoring the blood flow. It helps the physician understand the elasticity of the arterial walls, the amount of flow and the type of flow.
What can be diagnosed with a doppler ultrasound?
Doppler and color doppler ultrasounds are helpful in diagnosing many different conditions, including:
- Blood clots
- Deep Vein Thrombosis (DVT)
- Peripheral Arterial Disease (PAD)
- Carotid Artery Stenosis
- Leakage of heart valves (regurgitation)
- Coronary Artery Disease
- Venous insufficiency
- Arterial occlusion
- Abdominal aortic aneurysm
- Arteriosclerosis, the thickening and hardening of the arterial walls
- Atherosclerosis, the buildup of fats and cholesterol on the arterial walls.
- Fetal growth restriction (FGR)
What are symptoms that require a doppler ultrasound test?
Symptoms vary depending on the organ or tissues affected by cardiovascular abnormalities.
Carotid Artery Doppler Ultrasound
A carotid artery doppler is performed to assess the blood flow from the heart, through the carotid arteries to the brain. It can detect narrowed arteries known as carotid stenosis which can be due to the buildup of different types of plaques or deposits on the arterial walls. Carotid stenosis increases the risk of stroke.
Common symptoms of carotid artery stenosis include:
- Recent stroke
- Abnormal sound in the carotid arteries detected by the physician using a stethoscope during a routine examination
- Sudden numbness or weakness in the face or limbs affecting only one side of the body
- Sudden trouble speaking
- Sudden loss of balance, trouble walking, dizziness
- Sudden headache
Renal doppler is generally performed to assess the blood flow to the kidneys and diagnose renal artery stenosis (RAS) which is the narrowing of one or more of the arteries that supply the kidneys with blood.
Symptoms of renal artery stenosis include:
- Abnormal urine test results
- Abnormal kidney function blood test results
- Swelling of the body tissues
- High blood pressure
Venous doppler lower limbs
Venous doppler of the legs is generally performed to diagnose deep vein thrombosis (DVT) a condition due to a blood clot in the vein of a leg, or to diagnose chronic venous insufficiency (CVI) a condition where the valves in the leg veins don’t work properly.
Symptoms of deep vein thrombosis include:
- Pain in one leg
- Swelling in one leg
- Red or darkened skin in one leg
- Warm skin in one leg
Symptoms of chronic venous insufficiency include:
- Swelling in the ankles, feet and lower legs, especially after standing for a long time.
- Changes in the skin of the lower legs
- Varicose veins
- Aching and tiredness in the legs
- Ulcers on the lower legs
Arterial doppler lower limbs
Arterial doppler of the legs is generally performed to diagnose peripheral artery disease (PAD) which is the narrowing of the arteries in the extremities, most commonly the legs. Symptoms of PAD include:
- Pain or muscle cramping in the hips, thighs or calves when walking, climbing stairs or exercising.
- Numbness or weakness in the legs
- Cold legs or feet
- Change in color of the legs
Fetal doppler is routinely performed during pregnancy checkups starting around the 10th week. You can listen to the baby’s heartbeat during the second and third trimester by performing a fetal doppler. In high-risk pregnancies, it may be used to rule out fetal growth restriction, issues with the blood flow through the umbilical cord or issues with the placenta. High risk pregnancies include:
- Women with hypertension
- Women with diabetes
- Women who had previously lost babies during pregnancy
Doppler echocardiography may be prescribed to diagnose congenital heart disease, heart failure, heart valve disease as well as other conditions affecting the heart and the coronary arteries.
Symptoms of heart disease include:
- Shortness of breath
- Swelling in the lower limbs
- Angina (chest tightness, pain, pressure or discomfort)
Penile doppler ultrasound is an accurate and noninvasive way to evaluate the blood flow in the penis. For this reason, it is an effective diagnostic test for the diagnosis and assessment of erectile dysfunction (ED). ED is the inability to achieve and maintain an erection firm enough for sex.
Preparation for color doppler ultrasonography
To prepare for a color doppler ultrasound you may have to wear a disposable hospital gown or to remove clothing and jewelry to expose the area that needs to be examined.
In some cases, such as when the abdominal blood vessels are examined, you may have to fast for 6-12 hours before the procedure. For pelvic doppler ultrasound you may have to urinate 1-2 hours before the test and then drink 0,5-1 liter of water in order to have a full bladder during the procedure, which is required to properly perform it and visualize the area.
You should avoid smoking in the hours preceding the color doppler as nicotine constricts blood vessels and can affect the test results.
How is the color doppler ultrasound performed?
This procedure is similar to a regular ultrasound exam. You will have to lie on the examination table. A trained technician or a doctor will spread some water-based gel on the skin over the area to be examined. The healthcare provider will then slide the transducer, the ultrasound machine probe, over the area. The machine will show the images on a screen which will also be recorded. After the test is over the gel will be wiped off using disposable paper towels. You will have to lie still during the examination and may have to lie on your side or back, depending on the body part being scanned. You will hear the sound of your blood flow being emitted by the ultrasound machine.
How long does a color doppler ultrasound take?
A doppler ultrasound usually takes about 30-60 minutes. You will be ready to return to your daily activities immediately after the procedure.
Are there any risks to the test?
The color doppler ultrasound has no known risks. It is a safe procedure which doesn’t use any kind of harmful radiation, for this reason it is also safe during pregnancy.
The test is noninvasive and painless, you may just feel the pressure from the machine probe being pressed against your skin. If the area to be examined is tender, you may feel some pain.
- U.S. National Library of Medicine
- Radiological Society of North America (RSNA)
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