Marquette General Heart Institute

Ultrasound Doppler

A Doppler ultrasound study is a test that uses sound waves to evaluate blood flow inside the body. With this test, problems within the arteries can be detected. There is no radiation used in this test.

A hand-held instrument, called a transducer, is used in the test. It looks like a microphone, and sends and receives silent, high frequency sound waves. It is placed on the area of the body to be examined and moved with slight pressure across the area.

The transducer sends sound waves that pass through the skin into the body. They are reflected back to the transducer by the internal organs. These sound waves contain information that is changed into a picture of the area being examined. The sound waves are far above the range of human hearing.

A picture of the image is recorded and interpreted by a radiologist.

To test the blood flow, when the sound waves strike moving objects (like the red blood cells) the pitch of the sound is changed. This process is similar to the change in the pitch of a train whistle as the train passes.

The change in pitch can be displayed in several ways to evaluate blood flow within the body. An audible sound may be used or the flow may be shown as a graphic or color display.

ARTERIAL EVALUATION

Arteries carry oxygen-filled blood to nourish the cells of the body. A blockage in the arterial system prevents normal blood flow, causing pain, skin discoloration, numbness, loss of pulse, coldness and loss of feeling in the extremities.

LOWER EXTREMITIES

Arterial evaluation of the lower extremities is performed with the patient lying comfortably on his back while the technician places blood pressure cuffs on his arms, thighs, and ankles. Then a specialized instrument called a Doppler transducer is used to sense the blood flow and pressure at the ankle, behind the knee, and at the groin. Blood pressure readings are also taken in both arms. By graphically comparing these measurements, the location and extent of any arterial abnormality can be determined.

UPPER EXTREMITIES

For arterial evaluation of the upper extremities, the technician places a Doppler transducer under the arm, at the bend of the arm, and at the wrist. The Doppler monitors the blood flow in the artery. Then pressure readings are taken at the wrist with the blood pressure cuff being inflated at different points of the arm. Comparing all these readings helps the doctor determine the location of a possible blockage and the extent to which it is affecting circulation.

PREPARATION

Allow approximately one hour to completely finish your exam.

There is usually no discomfort involved in the test.

For most Doppler exams there is no preparation involved.

THE RESULTS

When your exam is completed, the radiologist will interpret the images. The results will be explained to you by your doctor.