Doppler Ultrasound Test

What do you mean by Doppler Ultrasound Exam of an Arm or leg?

A Doppler Ultrasound test uses ultrasound technology which measures the pitch of the sound waves as it gets reflected from blood vessels after hitting any obstruction. The Doppler ultrasound test is conducted especially on neck, arms and legs. The Doppler ultrasound test is also used to assess any kind of injury in the arteries and also to check the status of arterial reconstruction and bypass grafts. It at times also shows blocked or reduced blood flow due to the narrowing in the major arteries around the neck that may at times cause a stroke. It also reveals blood clots in the leg veins that may break loose and block blood flow towards the lungs. During pregnancy Doppler Ultrasound is used to look at the blood-flow of the unborn baby and also the health of the same.

There are basically four types of Doppler Ultrasound; they are; Bedside or Continuous Wave Doppler, Duplex Doppler, Color Doppler & Power Doppler.

What is Doppler Ultrasound Test?

Doppler Ultrasound test uses Ultrasound to examine and evaluate the blood flow in the major arteries and veins in the arms, legs and neck. With the help of the handheld instrument some sound waves are sent and received that are amplified through a microphone. The sound waves bounces back when it hits any solid object including blood cells. These obstructions causes a change in the movement of the sound waves which are then processes in a computer and then provided in graphs and pictures. On the other hand if there is no blood flow the pitch of the sound waves do not change. Result of the test is processed in a computer.

How is the test done?

The test is done by a specialized health provider or doctor, who specializes in performing and interpreting theses tests, or by an ultrasound technologist which is supervised by a radiologist. The Doppler ultrasound test is generally performed in an authorized ultrasound or radiology department or in a peripheral vascular laboratory. A water soluble gel is placed on a handheld device known as a transducer. The transducer in turn directs the high frequency sound waves to the artery or veins that are to be tested. It can also be done by applying some paste to the skin over the arteries that is to be examined. Images get created as the transducer moves over the different parts of the body where the test is been done.

How to prepare for the test?

The patient is asked not to use products that contain nicotine at least two hours before the test as nicotine may cause blood vessel to constrict and that may give false results. As the test will be going on the patient have to remove the clothing from arm or leg or the area that is being examined. The patient also has to remove all the jewellery if they are wearing any because it may interfere with the Doppler ultrasound scan. For abdominal scan one need to lie on their back, for chest one has to lie on their back with their neck slightly extended, for head and neck scan the head may be turned to one side and for arm and leg the head needs to be slightly raised and the exposed arm or leg needs to be turned slightly outward. The test usually takes 30-60 minutes, not more than that. 

Why is the test done?

This test is conducted as an alternative option to arteriography and venography. This test helps in diagnosing any presence of blood clot and blocked or narrowed blood vessel. The Doppler ultrasound test can be conducted for checking blood flow in almost every part of the body but is used especially for the neck, arms and legs. Blocked or narrowed arteries may cause dizziness, loss of vision, paralysis, weakness or other symptoms of stroke. This test also helps in evaluating cause of leg pain that may be intermittent claudication. It also diagnoses the problem in carotid artery blood flow caused by narrowing. The Doppler ultrasound test is also used to assess any kind of injury in the arteries and also to check the status of arterial reconstruction and bypass grafts.