Carotid and Vertebral Duplex Ultrasound (US)

What is Carotid and Vertebral Duplex Ultrasound (US)?

US uses sound waves to check how blood flows in the major arteries located on both sides of the neck. The carotid and vertebral arteries carry blood from the heart, through the neck, to supply the brain.

Your doctor may recommend this test to:

• Check for narrowing/stenosis in the arteries. These are commonly due to plaques.
• Investigate the possible cause of your symptoms, such as dizziness, vision problems and weakness.
• Monitoring arterial narrowing (stenosis) after surgery, stenting and/or medications.

How should I prepare for US?

• Avoid wearing clothing with a tight collar (e.g. avoid turtlenecks, choker necklace, scarf)
• Neck braces, tudung or tracheostomy collar may need to be temporarily removed for the test duration
• Not required to fast
• Continue with your regular diet and medications 
• If you feel unwell, please inform the lab prior to the test.

How is US performed?

The test is done by a sonographer and will take about 30 minutes to 1 hour.

• This test is done while you are lying down (face up) on the bed, with a low pillow 
• Clear, water soluble, ultrasound gel is applied to a side of your neck
• An ultrasound probe (hand-held device) is placed at different points of your neck to capture images along the blood vessel 
• Avoid moving and talking throughout the test so that clear images can be taken
• You may hear a “whooshing” sound – this is your blood flow
• The same process is repeated on the other side of the neck
• Once the test is done, the gel is cleaned off 
• A detailed report will be sent to your doctor within two weeks. Your doctor will discuss the findings with you at your next appointment.

Frequently Asked Questions about US

Is the test safe?

Yes, the test is: 

• Non-invasive (no needles)
• Radiation-free
• Widely used (the modality is similar to that for pregnancy scans)
• A sonographer will be present throughout the process. If you feel unwell, please inform the sonographer.

If you have any questions or concerns, please contact your designated neurodiagnostic laboratory or healthcare team.

Can I use Medisave to pay for this test?

This test may be claimable under:

• Flexi-MediSave for Seniors; or
• Outpatient scans for diagnosis or treatment of a medical condition.

Please refer to the Ministry of Health's Outpatient Care page for the latest claim limits and eligibility criteria.

The information is correct as of July 2026 and subject to revisions without notice.
Content adapted from NNI Neurodiagnostic Laboratory (NDL), NNI@TTSH.