Duplex Ultrasound

Duplex ultrasound shows how blood is flowing through your vessels and measures the speed of the flow of blood  and can estimate the diameter of a blood vessel as well as the amount of obstruction, if any, in the blood vessel.

Conventional ultrasound shows the structure of your blood vessels and the Duplex Doppler ultrasound shows the movement of your red blood cells through the vessels. Duplex ultrasound produces images that can be color coded to show physicians where your blood flow is severely blocked due to problems in the blood vessels (for example, cholesterol deposits) and the speed and direction of blood flow. When performing duplex ultrasound, your physician uses the two forms of ultrasound together:

  • Conventional ultrasound uses painless sound waves.  A computer converts the sound waves into two-dimensional, black and white moving pictures
  • Duplex Doppler ultrasound measures how sound waves reflect off of moving objects.

Who Benefits from Duplex Ultrasound

Your physician may recommend a duplex ultrasound to help diagnose and examine conditions that affect the blood vessels. These conditions include:

  • Carotid occlusive disease
  • Vertebral artery disease
  • Leg artery disease
  • Arm artery disease
  • Aortoiliac occlusive disease
  • Aneurysms in your abdomen or extremities.

Preparing for Duplex Ultrasound

  • For most types of duplex ultrasound you will not have to follow any special instructions
  • Abdominal duplex ultrasound might require preparation so check with your physician
  • Your physician may have specific instructions for a particular type of duplex ultrasound
  • You may be asked to fast overnight before having an abdominal ultrasound
  • Ultrasound waves cannot break through gas in the bowels or air in the lungs
  • No special medication is required and typically there is little discomfort

The Procedure

Duplex ultrasound can be performed in a laboratory, your physician's office or in a hospital setting.  The procedure can be administered by an ultrasound technologist or your physician and usually takes 30 minutes or so.

  • You will lie very still on a table with your head slightly elevated
  • A special gel, which may be cold when it first touches your body, will be spread over the area to be tested.  The gel allows for better transmission and reception of the ultrasound waves
  • The technician will press the ultrasound wand against your skin and moves it back and forth using slight pressure to get a better image.   The pressure may cause some mild discomfort, but most people usually do not find the test particularly painful
  • The movement of the wand sends images to the computer which the technician can view and record on a television-like screen
  • You may hear a whooshing sound, which is the sound that the ultrasound machine makes to represent your blood moving through your body
  • There are no special instructions for you to follow after the test. You may resume all of your pre-test activities. 
  • Since the test is usually painless, sedation is not routinely required.

Possible Complications

Complications are very rare with ultrasound examinations.  Do not hesitate to discuss any concerns with your physician.