Doppler ultrasound is a test that uses high frequency sound waves (ultrasound) to measure the amount of blood flow through arteries and veins of different parts of the body. During Doppler ultrasound , a handheld device is passed lightly over the skinabove 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 not change.
Theoretically, with the help of ultrasound one can assess the condition of many of the arteries and veins of the body, but Doppler ultrasound has a special clinical value in the following areas:
Avoid smoking or drink coffee and strong tea for at least two hours before the test. Smoking and caffeine use can shrink your blood vessels and affect the accuracy of the test.
You should wear comfortable, loose-fitting clothing for your ultrasound exam. You may need to remove all clothing and jewelry in the area to be examined.
You may be asked to wear a gown during the procedure.
For most ultrasound exams, you will be positioned lying face-up on an examination table that can be tilted or moved. Patients may be turned to either side to improve the quality of the images.
A clear water-based gel is applied to the area of the body being studied to help the transducer make secure contact with the body and eliminate air pockets between the transducer and the skin that can block the sound waves from passing into your body. The sonographer (ultrasound technologist) or radiologist then places the transducer on the skin in various locations, sweeping over the area of interest or angling the sound beam from a different location to better see an area of concern.
Doppler sonography is performed using the same transducer.
When the examination is complete, you may be asked to dress and wait while the ultrasound images are reviewed.
This ultrasound examination is usually completed within 30 to 45 minutes. Occasionally, complex examinations may take longer.