What Is Doppler Ultrasound: Purpose and Procedure Details

Healthcare providers use Doppler ultrasound to evaluate heart and blood vessel (cardiovascular) conditions. This test measures the direction and speed of blood flow through arteries and veins, helping to detect issues such as blood clots, narrowed arteries, and other circulatory problems affecting the heart, as well as blood vessels in the arms, legs, and abdomen.

Overview  

What is a Doppler ultrasound?  

A Doppler ultrasound is a diagnostic tool that uses sound waves to create images of blood flow within your circulatory system. It shows how fast and in what direction blood is moving through your arteries and veins, including blood flow in your heart.

Healthcare providers use Doppler ultrasound results to diagnose and monitor cardiovascular conditions.

What are the types of Doppler ultrasounds?  

Ultrasound—also known as sonography or ultrasonography—is a noninvasive imaging technique. While a standard ultrasound provides detailed images of internal structures, it does not capture blood flow. In contrast, a Doppler ultrasound is specifically designed to visualize and assess blood movement.

There are several types of Doppler ultrasounds, including:

- Color Doppler: A computer changes the sound waves into different colors to show the direction of blood flow.

- Spectral Doppler: Graphical representation of blood flow over time.

- Duplex ultrasound: Combines traditional ultrasound pictures with Doppler ultrasound. It can check the width of blood vessels and can help show blockages.

- Power Doppler: This type of Doppler ultrasound detects the presence of blood flow, including very slow flow that might not be visible with other methods. However, it does not indicate the direction of the blood flow. Healthcare providers often use power Doppler to evaluate blood circulation within organs.

- Transcranial Doppler ultrasound: This technique assesses blood flow in the brain and is commonly used to detect conditions such as strokes or subarachnoid hemorrhages.

Who might need a Doppler ultrasound?  

Healthcare providers use Doppler ultrasound to:

- Diagnose conditions affecting blood vessels in the abdomen, legs, or arms  

- Monitor blood flow following surgery or certain treatments  

- Evaluate blood circulation between a pregnant individual and the fetus during pregnancy  

What conditions can Doppler ultrasound help diagnose?  

Doppler ultrasound can assist in identifying:

- Narrowed or blocked arteries and veins  

- Blood clots, including deep vein thrombosis (DVT)  

- Blood vessel injuries  

- Chronic venous insufficiency (CVI)  

- Blood flow to transplanted organs such as the kidney, liver, or pancreas  

- Renal vascular causes of high blood pressure  

- Tumors involving blood vessels

How does a Doppler ultrasound work?  

A Doppler ultrasound uses a handheld probe to send sound waves into your body. These sound waves bounce off moving blood cells within your blood vessels and return to the probe. A computer analyzes the change in pitch between the transmitted sound waves and the returning echoes to determine the direction and speed of blood flow.

This helps evaluate:

- The speed of blood flow and overall circulation  

- Any blockages or obstructions affecting blood flow  

- Blood flowing in the wrong direction or pooling within a vessel  

How should I prepare for a Doppler ultrasound?  

Preparation may vary depending on the type of test and its purpose. You may be asked to:

- Avoid eating or drinking (fast) for a specific number of hours before the exam  

- Refrain from smoking or using nicotine products for at least two hours prior, as nicotine can constrict blood vessels and impact test accuracy

What happens during a Doppler ultrasound?  

A Doppler ultrasound is performed by a sonographer, a specialist trained in ultrasound imaging. The procedure typically lasts between 30 and 60 minutes.

Depending on the area being examined, you may be asked to lie on your back, your side, or sit upright on an exam table.

During the procedure:

- A small amount of gel is applied to your skin to help the probe (transducer) glide smoothly and improve the transmission of sound waves.  

- The transducer emits painless, high-frequency sound waves into your body. These waves are inaudible.  

- As the sound waves bounce off moving blood cells, they change pitch. You may hear a whooshing sound from the machine as it captures this movement.  

- The transducer detects these changes, and a computer processes the information into images or graphs that your healthcare provider can analyze.  

- Once the test is complete, the gel is wiped off your skin.  

What are the risks of a Doppler ultrasound?  

Doppler ultrasound is a safe, noninvasive test with minimal risk. Unlike angiograms, it does not require contrast dyes, and unlike X-rays or CT scans, it does not use radiation. The procedure is painless and safe for use during pregnancy.