The term “ultrasound” usually suggests a pregnant woman in her doctor’s office checking on her baby. But while fetal imaging is one of the most common uses of ultrasounds, this diagnostic tool has many other applications especially in pain management and today’s vein clinics.
In the early stages of ultrasound, Doppler was used in measuring the speed of blood flowing through the blood vessels. These machines emitted ultrasound waves, and a receiver picked up echoes which were translated into sounds. Such machines are still in use to measure fetal heart rate, for instance.
Duplex ultrasound, first introduced in 1974, is a modern ultrasound scanning machine. Today, the modern duplex scanner, using two kinds of ultrasound, can help find vascular disease throughout the body. It is a noninvasive test that can show the anatomy of an organ as well as measure blood through blood vessels. Duplex ultrasound tests go by many names, sometimes they are also called:
- Doppler Test
- Duplex Exam
- Duplex Scan
- Ultrasound Exam
- Vascular Lab Test
In This Article:
- What Is Duplex Ultrasound?
- How Does Duplex Ultrasound Work?
- Conditions Treated with Duplex Ultrasound
- What Are the Benefits of Duplex Ultrasound?
- Novus Spine & Pain Center
- Duplex Ultrasound Resources
What Is Duplex Ultrasound?
Pain management doctors use duplex ultrasound tests to see how blood moves through the blood vessels. The term “duplex” refers to the fact that a duplex ultrasound uses both Doppler and conventional ultrasound imaging. Traditional ultrasound uses sound waves to create a picture of the blood vessels while Doppler sound waves measure the speed and other aspects of blood flow.
In addition to measuring blood flow, duplex ultrasound can help in diagnosing problems with muscles, the heart, and various organs.
How Does Duplex Ultrasound Work?
The transducer of an ultrasound machine emits sound waves at a frequency too high to be heard by the human ear. The process works with a transducer (a device similar to a microphone) that obtains an image of a blood vessel (or other soft tissue) that displays the direction and flow velocity of the blood.
Placing the transducer on the skin, allows ultrasound waves to move through the body to the organs and structures within. When these sound waves hit an organ, they return to the transducer (like an echo). A computer converts the reflected waves into an image of the organs or tissues being examined. An image is possible because sound waves travel at different speeds, depending on the type of tissue they strike or encounter. A computer translates the rate at which the sound waves return to the transducer, as well as how much of the sound wave returns, into an image of the body tissue it strikes.
Ultrasound cannot travel through the air. So, to begin, a special gel is spread on the patient’s skin to eliminate air between the skin and the transducer. The gel helps obtain the best sound conduction and allows for smooth movement of the transducer over the skin. The doctor may move the transducer back and forth to get the best images of the underlying blood vessels and any blood clots that may exist.
Doppler ultrasound helps the doctor measure the speed and direction of blood flow in arteries and veins, or blood flow to an organ. Unlike a standard ultrasound, a “swishing” sound is audible from the Doppler ultrasound which is the sound of the blood moving.
The procedure is painless and easy for the patient, typically lasting about 30 minutes; however, the duration varies depending on the structure being examined. Depending on the specific test, the position of the patient will also vary.
If the scan is for varicose veins or venous reflux, it is important that the blood can reflux (pool) due to gravity. For this to happen, scans for venous reflux are usually performed with the patient standing to allow the equipment to pick up any venous reflux.
When scanning for a deep vein thrombosis (DVT) or thrombosis of the superficial veins (superficial thrombophlebitis) the test is performed with the patient lying down. It is essential the patient remain still during the examination to help ensure clear images.
Duplex ultrasound has many advantages over other imaging methods. Besides being noninvasive, the test is easily mobile and well tolerated by patients. Additionally, it does not expose the patient to possible kidney damage from the injection of a contrast dye (nephrotoxicity), or radiation. The test can also be performed on patients with implants.
Conditions Treated with Duplex Ultrasound
A duplex ultrasound is a first step in looking at arteries and veins and can help in diagnosing:
- Arteriosclerosis (thickening or hardening) of the arteries in the arms or legs.
- Blood clots (deep vein thrombosis or DVT).
- Venous insufficiency.
The test can also be used to:
- Look at injury (trauma) to arteries or veins.
- Monitor arterial reconstruction and bypass grafts.
- Find narrowing blood vessels that may be causing leg pain when walking.
- Diagnose resting leg pain.
- Analyze foot, ankle, heel or toe ulcers.
- Determine the reason for skin discoloration.
- Thrombophlebitis (an inflammation of the blood vessels that causes a blood clot to form and block one or more veins).
- Raynaud’s phenomenon (a spasm of small blood vessels that makes body parts feel numb and cool in low temperatures or under stress, usually occurring in the fingers, toes, nose and ears).
Duplex ultrasound can also be used in conjunction with other tests, such as the measurement of blood pressure in the legs, or when testing for reduced blood flow in the arms or legs.
What Are the Benefits of Duplex Ultrasound?
There are many advantages of using duplex ultrasound for diagnostic procedures:
- They are generally painless.
- They do not require needles, injections, or incisions.
- Patients aren’t exposed to ionizing radiation, making the procedure safer than X-rays and CT scans.
- Ultrasound captures images of soft tissues that don’t show up well on X-rays.
- Ultrasounds are widely accessible and less expensive than other methods.
Novus Spine & Pain Center
Novus Spine & Pain Center is in Lakeland, Florida, and treats patients with chronic pain with numerous therapies including duplex ultrasound. By using a comprehensive approach and cutting-edge therapies, we work together with patients to restore function and regain an active lifestyle, while minimizing the need for opiates.
Duplex Ultrasound Resources
Doppler Ultrasound (Free Dictionary/Medical)
How is a duplex ultrasound used to diagnose deep vein thrombosis (DVT)? (WebMD)
What Is an Ultrasound? (WebMD)
Duplex Ultrasound (Medline Plus)
Doppler ultrasound exam of an arm or leg (Medline Plus)
Duplex Ultrasound (Society for Vascular Surgery)
Arterial Duplex Ultrasound – Legs (Cedars-Sinai)
Venous Duplex Ultrasound – Legs (Cedars-Sinai)
How Is Duplex Ultrasonography Performed? (College of Phlebology)
Is There a Difference Between Doppler and Duplex Ultrasound? (Quora)
Duplex Ultrasound (Stanford Healthcare)
Ultrasound (Johns Hopkins)
Duplex Ultrasound (PubMed)
History of Ultrasonic Duplex Scanning (SAGE Journals)
Image Credit: Wikimedia