A Doppler ultrasound is a test that uses high-frequency sound waves to measure the amount of blood flow through your arteries and veins. It helps doctors assess and check blocked or reduced blood flow through major arteries and veins, such as those of the arms, legs, and neck. 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. 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 called transducer is passed lightly over the skin above a blood vessel. 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 not change. Information from the reflected sound waves is used to make graphs or pictures that show the flow of blood through the blood vessels. These graphs or pictures are saved and evaluated.
Color Doppler uses standard ultrasound methods to make a picture of a blood vessel. A computer changes the Doppler sounds into colors that are overlaid on the image of the blood vessel. These colors show the speed and direction of blood flow through the vessel.
A Doppler ultrasound test uses reflected sound waves to see how blood flows through a blood vessel. Doppler is done to helps doctors assess the blood flow through major arteries and veins. A reduced amount of blood flow may be due to a blockage in the artery, a blood clot inside a blood vessel, or an injury to a blood vessel. Doppler is mainly done to:
Check the health of a foetus. It may check blood flow in the umbilical cord, through the placenta or in the heart and brain of the foetus. This test can show if the foetus is getting enough oxygen and nutrients.
A venous Doppler ultrasound is a diagnostic test used to check the circulation in the large veins in the legs (or sometimes the arms) for any blockage in the veins by a blood clot or thrombus formation.
An arterial doppler is an ultrasound exam of the arteries located in your arms or legs. High frequency sound waves are used to obtain images of structures inside the body. Ultrasound imaging can help the radiologist see and evaluate arterial blockages, such as plaque in arteries.
Ultrasound is performed to create a "map" of your leg veins for the surgeon in preparation for various procedures that will include bypass graft surgery (replacing diseased vessels in your body with the healthy vein from your leg).