What is Doppler Ultrasonography? A Guide

Doppler ultrasonography is a type of ultrasound scan that health professionals use to get a closer look at your blood flow. Non-invasive, painless and completely safe, doppler ultrasonography produces results almost instantly.

Ultrasonography has been widely used by doctors since the 1960s to assess a range of conditions and diseases. The technique uses sound waves to create a picture of internal body structures like tendons, muscles and organs. It’s also commonly used in pregnancy to assess the condition of the baby and spot any abnormalities.

Normal types of ultrasound, although incredibly useful in the diagnostic process, don’t show blood flow. If doctors want to assess the condition of blood vessels, and the rate of blood flow in the body, they need to use Doppler ultrasonography.

A Doppler ultrasound can be used by health professionals to identify a number of conditions and to aid diagnoses. Incredibly useful, this quick, non-invasive technique can save lives and help doctors to provide top-level care.  

What is the Difference Between a Doppler and an Ultrasound?

A Doppler is a type of ultrasound that’s used to measure or assess the flow of blood in the body. Doppler ultrasonography uses sound waves to build a picture of how blood is moving in a patient’s vessels. The technique can be used to measure the speed and direction of blood in the body and is a valuable technique for diagnosing and monitoring a range of diseases and conditions.

Doppler ultrasounds are carried out using small, handheld devices. These are simply placed against the patient’s skin and then adjusted until the person carrying out the scan gets a satisfactory reading. The patient shouldn’t experience any pain or discomfort during a Doppler ultrasound.

What is the Doppler in an Ultrasound?

The ‘Doppler’ in a Doppler Ultrasound refers to the Doppler Effect, or Doppler shift. This was first identified in the mid-19th century by Austrian physicist Christian Doppler. It describes the increase or decrease in the frequency of sound, light, or other waves as the source of the waves and the observer move towards or away from each other.

A Doppler ultrasound bounces sound waves off of the blood circulating in a patient’s body. This allows the doctor or sonographer carrying out the test to build up a detailed and informative picture of the patient’s vessels. Often, the device used to carry out this type of scan is referred to as a Doppler. 

What is Doppler Flow?

Doppler flow is a type of Doppler ultrasound. Like other types of Doppler ultrasound, it uses sound waves to measure the flow of blood through a vessel. Waveforms of the blood flow are shown on the ultrasound screen, allowing the professional carrying out the scan to assess the patient’s circulation.

Doppler flow studies are often used to assess the blood flow in a baby’s umbilical vein and arteries. It can also be used to check the foetal brain, foetal heart and other internal organs. Doppler flow is sometimes called Doppler velocimetry 

What is A Doppler Ultrasound Used For? 

Doppler ultrasounds are commonly used to assess patients suffering from symptoms that indicate there is an issue with the circulatory system. For example, if a doctor believes a patient is experiencing reduced blood flow or heart disease they may use a Doppler to get more information about the patient’s blood vessels and flow. 

Dopplers allow doctors to make quick and accurate assessments and help them to decide if further treatment is needed.

Symptoms that may result in a Doppler ultrasound include: 

  • Numbness or weakness in the legs
  • Painful cramping in the hips or leg muscles when walking or climbing stairs
  • Cold feeling in the lower leg or foot
  • Change in colour and/or shiny skin on your leg
  • Shortness of breath
  • Swelling in the legs, feet, and/or abdomen
  • Fatigue

 Patients may also require a Doppler if:

  • They’ve had a stroke - Transcranial Dopplers can be used to check blood flow to the brain
  • They have injured their blood vessels
  • They are being treated for a known blood flow disorder
  • If they are pregnant and their doctor believes there may be a blood flow problem with mother or baby.  

What Can a Doppler Ultrasound Detect?

A Doppler ultrasound can be used to detect and diagnose a range of conditions and diseases related to the circulatory system. These include:

  • A blocked artery (arterial occlusion)
  • Decreased blood circulation into the legs (peripheral artery disease)
  • Bulging arteries (aneurysms)
  • Narrowing of an artery (carotid artery stenosis)
  • Deep vein thrombosis (DVT)
  • Blood clots
  • Poorly functioning valves in leg veins. These can cause blood and other fluids to pool in the legs (venous insufficiency)
  • Heart valve defects and congenital heart disease

Many of these conditions, like aneurysms and blocked arteries, are very serious if they’re not treated quickly. This is one of the reasons that the fast, accurate results produced by Doppler ultrasonography are so useful.

How to Perform a Doppler Ultrasound 

Sonographers and most doctors will learn how to do a Doppler ultrasound as part of their training. Some specialist nurses will also be taught how to use a Doppler ultrasound and read the results.

If you’re a patient, you won’t have to do anything during your scan, so you don’t need to worry about how to use a vascular Doppler. The doctor, nurse or sonographer will first apply a little gel to your skin. This helps the soundwaves to travel into your body and provides more accurate results. They will then put the handheld Doppler probe on the affected area and move it around until they get the correct reading. 

How to Read a Doppler Ultrasound 

The way a Doppler is read will depend on the exam being carried out. For example, a lot of foetal Dopplers are mostly used to check the baby’s heartbeat. In this instance, a simple heart rate reading will probably be sufficient to give the doctor or sonographer the information they need. 

If the doctor or sonographer is checking for an aneurysm, DVT or another circulatory condition, they may use another type of Doppler. Common types of Doppler ultrasonography include:

  • Colour Doppler - This uses a computer to change sound waves into different colours which show the speed and direction of blood flow in real time.
  • Power Doppler – This is a type of colour Doppler that can provide more detail about blood flow than a standard colour Doppler. However, it can’t show the direction of blood flow.
  • Spectral Doppler – This type of Doppler shows blood flow data on a graph, rather than colour images. It’s often used to see how much of a blood vessel is blocked.
  • Continuous wave Doppler – When this type of Doppler is carried out, sound waves are sent and received continuously. This provides a more accurate measurement of blood when it is flowing quickly.


How to Interpret a Doppler Ultrasound

Again, the way a Doppler is interpreted will depend on what the doctor is looking for and which type of Doppler has been carried out. If your readings fall outside normal parameters, your doctor will talk you through the results and what they mean for your diagnosis.

How to do a Doppler Ultrasound in Pregnancy

Because they are small, easy to use and accurate, Dopplers are commonly used to check a baby’s heart rate during pregnancy. In many cases, family doctors will learn how to read a Doppler ultrasound in pregnancy to allow them to monitor mother and baby without the need for a hospital visit.

When a Doppler ultrasound is carried out in pregnancy, gel will be placed on the mother’s belly and a specially designed foetal doppler applied to the skin. The doctor or sonographer will then move the probe around until they get a clear reading of the baby’s heartbeat. This process should be painless and non-invasive. However, in some cases, the sonographer may need to apply some pressure in order to get an accurate reading.  

Doppler ultrasonography is an incredible medical tool that provides valuable information on a range of conditions. Learn more about Doppler ultrasonography, and about the Dopplers in our collection of high quality medical devices by exploring the Medshop store today or contacting one of our advisors.

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