What is doppler?
A Doppler ultrasound test uses reflected sound waves to evaluate blood as it flows through a blood vessel. It helps doctors evaluate blood flow through the major arteries and veins of the arms, legs, and neck. It can show blocked or reduced blood flow through narrowing in the major arteries of the neck that could cause a stroke. It also can reveal blood clots in leg veins that could break loose and block blood flow to the lungs.
How is it done?
During Doppler ultrasound, a hand-held instrument (transducer) is passed lightly over the skin above a blood vessel. The transducer sends and receives sound waves that are amplified through a
During Doppler ultrasound, a hand-held instrument (transducer) is passed lightly over the skin above a blood vessel. The transducer sends and receives sound waves that are amplified through a microphone. The movement of blood cells causes a change in pitch of the reflected sound waves (called the Doppler effect).
If there is no blood flow, the pitch does not change. Information from the reflected sound waves can be processed by a computer to provide graphs or pictures that represent the flow of blood through the blood vessels. These graphs or pictures can be saved for future review or evaluation.
Types of Doppler studies:
1.Bedside or continuous wave Doppler
2.Duplex Doppler
3.Colour Doppler
4.Power Doppler
Why is it done?
- Detect blood clots and blocked or narrowed blood vessels in almost any part of the body, especially in the neck, arms, and legs. Blocked or narrowed arteries of the neck can cause dizziness, loss of vision, paralysis, weakness, numbness, or other symptoms of a stroke. Blood clots in the deep veins of the leg can cause leg pain and swelling and can increase a person’s risk of pulmonary embolism.
- Evaluate blood flow after a stroke or other condition that might be caused by a problem with blood flow. Evaluation of a stroke can be done through a technique called transcranial Doppler (TCD) ultrasound.
- Map veins that may be used for blood vessel grafts. It also can evaluate the condition of grafts used to bypass a blockage in an arm or leg.
- Determine the amount of blood flow to a transplanted kidney or liver.
- Monitor the flow of blood following blood vessel surgery.
- Determine the presence, amount, and location of arterial plaque. Plaque in the carotid arteries can reduce blood flow to the brain and may increase the risk of stroke.
- Doppler studies can also be done in pregnant ladies safely to evaluate uteroplacental and fetoplacental circulation.
How does it feel to undergo a doppler test?
There is no discomfort or risks associated with Doppler studies.
What affects the test?
Factors that can interfere with your test and the accuracy of the results include:
- Bones above the area being studied or gas in the intestines.
- The inability to remain still during the test.
- Extreme obesity.
- Having a cold arm or leg. Blood flow through that limb may be slowed.
- Having an open wound in the area that needs to be viewed.
Producing accurate test results with Doppler ultrasound requires a skilled examiner. The scans are usually read within a short period of time.Because Doppler ultrasound requires a person to hold very still, some children may need to be sedated so that their movements do not interfere with the results.Angiography and venography are
Angiography and venography are x-ray tests that require the injection of contrast material. In many cases, Doppler ultrasound may be done instead of angiography or venography, since it is faster, less expensive, and noninvasive. If results from a Doppler ultrasound are inconclusive, an angiography or venography test may be done.
Pic courtesy: medicalexpo.com
Content Courtesy: Bharat Scans