A duplex ultrasound scan combines traditional ultrasound technology with Doppler ultrasound. This diagnostic tool uses sound waves to produce images of the inside of the body, allowing medical professionals to observe the structure of blood vessels, organs, and tissues.

The term “duplex” refers to the two modes of ultrasound used: B-mode, which provides a visual representation of the tissue structures, and Doppler mode, which measures and visualises the blood flow within the vessels.

Purpose of Duplex Ultrasound Scans

Unlike conventional ultrasound, which is limited to capturing static images of internal body structures, duplex ultrasound allows for the visualising of the dynamic blood flow.

Its primary purpose is to comprehensively evaluate the body’s vascular system, particularly the arteries and veins.

Blood Flow Assessment: Duplex ultrasound scans can measure the speed and direction of blood flowing through the vessels. This information is crucial in diagnosing conditions such as arterial occlusions, venous insufficiency, and peripheral arterial disease.

Detection of Vascular Abnormalities: Through the detailed images provided by duplex scans, a medical specialist can identify abnormalities such as blood clots, blockages, plaque buildup, and aneurysms in the vascular system.

Monitoring Treatment: For patients undergoing treatment for vascular diseases, duplex ultrasounds are essential for monitoring the effectiveness of interventions, such as surgery or medication.

Types of Duplex Ultrasound Scans

The most common types of duplex ultrasound scans include:

Carotid Duplex Ultrasound

This type of scan can visualise the carotid arteries, which supply blood to the brain. It helps in detecting plaques and blockages that could lead to stroke.

Venous Duplex Ultrasound

Venous duplex ultrasound is often employed to identify blood clots, especially in the legs, known as deep vein thrombosis (DVT). It can also assess the condition of the venous valves and the presence of chronic venous insufficiency.

Arterial Duplex Ultrasound

This scan focuses on the arteries in the body, excluding the heart. It’s used to detect blockages, narrowing of arteries, or aneurysms, particularly in the legs, arms, and neck.

Abdominal Duplex Ultrasound

Abdominal duplex scans examine the abdominal aorta and other blood vessels in the abdomen. This scan can identify aneurysms, renal artery stenosis, and other vascular conditions in the abdominal area.

Renal Duplex Ultrasound

Renal duplex ultrasound assesses the blood flow to and from the kidneys, helping to identify conditions such as renal artery stenosis, which can cause hypertension and affect kidney function.

Preparing for a Duplex Ultrasound Scan

Patients may be advised to follow some simple steps to ensure accurate results:

Fasting

Patients may be advised to fast for 6 to 8 hours before the procedure for abdominal scans. This reduces the amount of gas in the intestines and improves the visibility of abdominal structures.

Clothing

Patients are usually asked to wear loose-fitting, comfortable clothing and may be required to change into a hospital gown.

For neck, arms, or leg scans, clothing that easily exposes these areas is recommended.

Medications

It’s important to inform the medical specialist about all medications being taken, as some might affect blood flow.

Special Instructions

Depending on the specific area being scanned and the patient’s medical history, additional instructions may be given. These include avoiding smoking or caffeine before the scan, as they can affect blood flow. Generally, duplex ultrasound scans require minimal preparation, making them a convenient diagnostic tool.

What to Expect During the Procedure

A duplex ultrasound scan is a simple, non-invasive procedure. Here’s a streamlined overview of what happens during the scan:

• Application of Gel: A technician applies a special gel to the examined area, which helps transmit the ultrasound waves.
• Using the Transducer: The technician moves a handheld device (transducer) over the skin to capture images and, if necessary, sound waves of blood flow.
• Position Changes: You may need to shift positions to get clear images from different angles.

Interpreting Duplex Ultrasound Results

Interpreting the results of a duplex ultrasound involves analysing both the structural images of blood vessels and the flow of blood through these vessels. Here’s a simplified overview of what the results might indicate:

Blood Flow and Velocity

Normal Blood Flow: A smooth, consistent flow pattern usually indicates healthy vessels.

Abnormal Blood Flow: Turbulence or a change in the direction of blood flow can signal blockages, narrowing of vessels, or other abnormalities.

Vessel Structure

Normal Vessels: Uniformity in vessel walls and diameter is typically a sign of healthy blood vessels.

Abnormal Findings: Irregularities such as bulges, narrowing, or plaque buildup point to potential vascular issues.

Specific Conditions

The results can help diagnose various conditions, such as:

Peripheral Artery Disease (PAD): Detected through abnormal blood flow or structural changes in the arteries.

Deep Vein Thrombosis (DVT): Identified by the presence of blood clots or impaired blood flow in the veins.

Carotid Artery Disease: Revealed by narrowed or blocked carotid arteries, increasing stroke risk.

Follow-up

Depending on the findings, your doctor may recommend further testing, lifestyle changes, medication, or, in some cases, surgery.

Conclusion

Duplex ultrasound scans are a critical advancement in diagnostic imaging, offering a non-invasive, safe, and effective method for evaluating the body’s vascular system. By combining traditional ultrasound imaging with Doppler technology, these scans provide comprehensive insights into both the structure of blood vessels and the dynamics of blood flow. Duplex ultrasound facilitates informed decision-making in managing vascular diseases, guiding treatment planning and assessing the efficacy of interventions.