Doppler ultrasound gives doctors a visual or audible representation of blood movement through veins, arteries and blood vessels with sound waves. The reflected sound can be used to diagnose restricted blood flow, blood clots, and fetal health. Unlike ultrasound imaging used to give parents a picture of baby in-utero, Doppler ultrasound is used to view blood flow in the fetus.

Doppler Ultrasound tests are conducted with a handheld device known as a transducer. There are three main types of Doppler Ultrasound: continuous, duplex and color.

Continuous Doppler Ultrasound

Also referred to as “Bedside Ultrasound,” continuous Doppler ultrasound uses reflected sound waves as an audible diagnostic tool. The doctor uses a small, portable unit to listen to the reflected sounds. Blocked blood vessels make a certain sound as do narrowed and open blood vessels. This type of Doppler ultrasound is used for a quick diagnosis of potential restrictions in blood flow.

Duplex Doppler Ultrasound

The duplex Doppler ultrasound produces a visual picture with sound waves. As sound waves bounce off blood vessels an image is created. The sounds are also converted to graphs using a computer program to evaluate the direction of blood flow and the speed at which blood is moving.

Color Doppler Ultrasound

Color Doppler ultrasound is similar to duplex Doppler ultrasound in that a picture is created from sound waves. Instead of the sounds being converted into a graph, a color picture of blood flow speed and movement is created from the sounds.

Power Doppler Ultrasound

Power Doppler is a form of Color Doppler Ultrasound that is able to penetrate organs for a closer look at what’s going on with blood flow inside the organ. The resulting image includes a color overlay showing blood speed and direction.

Why Is Doppler Ultrasound Used During Pregnancy?

There are various diagnostic uses for Doppler ultrasound in a traditional medical setting, but in terms of pregnancy and fetal and pregnancy health, uses are limited. Doctors often use Doppler ultrasound during pregnancy to check fetal umbilical blood flow, placental blood flow and blood flow in the heart and brain. Using the Doppler ultrasound results, doctors can determine if restricted blood flow due to sickle cell anemia, RH sensitization or restricted blood vessels is to blame for fetal abnormalities.

Restricted blood flow to the fetus could cause:

• Lower birth weight
• Reduced size
• Impaired development

If sickle cell anemia is diagnosed, children may undergo a special form of Doppler ultrasound known as the transcranial Doppler to evaluate the risk of stroke.