Doppler flow is a type of ultrasound. It uses sound waves to measure the flow of blood through a blood vessel. The results are shown on a computer screen in lines called waveforms. It's sometimes called Doppler velocimetry. A Doppler flow study may be used during pregnancy to check the health of the unborn baby (fetus). It checks blood flow in:

• The umbilical vein and arteries.
• The baby's brain.
• The baby's heart.
• Other organs in the baby.

A Doppler flow study is often used when a baby has intrauterine growth restriction. This is when the baby is smaller than normal for the number of weeks of pregnancy. The waveforms may show that there isn't enough blood flow in the umbilical vessels of a baby with fetal growth restriction. This can mean that the baby may not be getting enough blood, nutrients, and oxygen from the placenta. Doppler flow is often used if you are pregnant with two or more babies (multiple pregnancy).

The Doppler flow study is a noninvasive test. The test doesn't harm you or the baby.

You don't need to do any special preparation before the test.

You will lie in a comfortable position on an exam table. A doctor with special training does this test using a special ultrasound machine. Gel is put on your belly. This helps to send sound waves from your belly to the computer. The doctor puts a device called an ultrasound transducer on your belly. It takes several minutes to check the flow in each blood vessel being tested.

The doctor will talk with you about the results. If the test shows there is not enough blood flow, you may need other testing.

Before you agree to the test or procedure, make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• When and where your you are to have the test or procedure
• Who will do the procedure and what that person's qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how you will get the results
• Who to call after the test or procedure if you have questions or problems
• How much you will have to pay for the test or procedure