Color Doppler ultrasound is a medical imaging technique which is used to provide visualization of the bloodflow, using color processing to add color to the image so that a doctor or care provider can clearly see what is happening inside the body.
A Doppler ultrasound test uses reflected sound waves to see how blood
flows through a blood vessel. It helps doctors evaluate blood flow
through major arteries and veins, such as those 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. During pregnancy, Doppler ultrasound may be used to look at blood flow in an unborn baby (fetus) to check the health of the fetus.
During Doppler ultrasound, a handheld 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 sound waves bounce off solid objects, including blood cells. 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.
How To Prepare
You may need to stop using products that contain nicotine (cigarettes, chewing tobacco) for 30 minutes to 2 hours before the test. Nicotine causes blood vessels to constrict and may give false results.
You will need to remove any jewelry that might interfere with the Doppler ultrasound scan. You may need to take off all or most of your clothes, depending on which area is being examined.
Gel is applied to the skin to promote the passage of the sound waves. The transducer is placed in the gel and moved along the skin. You need to lie very still during the procedure. You may hear sounds that represent the flow of blood through the blood vessels.
The test usually takes 30 to 60 minutes