What is a Doppler ultrasound?
A Doppler ultrasound is a non-invasive test that calculates the flow of blood through blood vessels. The device combines regular ultrasound, which bounces sound waves off objects, with the Doppler effect to determine the speed at which objects (in this case, red blood cells) are moving.
The test is known as Doppler ultrasound because Christian Doppler is the one who described how the tone coming from an object differs depending on its speed. This is like the effect of a car engine – as the vehicle approaches, the pitch is higher and as it moves away it decreases. The effect is used in everything from radar to astronomy.
A Doppler ultrasound does not cause pain or discomfort.
What does it consist of?
In a Doppler ultrasound, a device is passed over the skin in the area to be examined. The device sends high-frequency sound waves to bounce off red blood cells, measuring blood flow in a particular blood vessel.
A gel is applied to the skin, depending on the location of the blood vessels to be examined. A device (the transducer) is then passed over the skin. Sphygmomanometers may be used to compare blood pressure.
What is it used for?
A Doppler ultrasound is used to detect blood flow which in turn can help diagnose a multitude of conditions including blood clots, blocked or narrowed arteries, and aneurysms (bulging arteries) among others. It can also be used to monitor blood flow after surgery and even to monitor a baby’s health before birth. How to prepare for it? The technique is noninvasive and very little preparation is needed. Loose clothing is advised and items such as ties or stockings may need to be removed, as a device must be passed over the skin. It may also be necessary to stop smoking, as nicotine can narrow the blood vessels.
What does the procedure feel like?
A Doppler ultrasound does not cause pain or discomfort, although patients may hear the sound of blood passing through their arteries, experiencing a whooshing sound.
What could a ‘bad’ result mean?
The results are interpreted to determine if there is a narrowing or blockage in the arteries. Normal results indicate that the blood pressure is normal and there is no narrowing or blockage. A ‘bad’ result would be indicated by the detection of atypical blood flow which may be indicative of some conditions. These results will be interpreted by a specialist.