Doppler ultrasound is used in pregnancy to study blood circulation in the baby, uterus and placenta. It uses sound waves to detect the movement of blood in vessels. Those sound waves then are reflected back towards the ultrasound probe that is on the maternal abdomen. By comparing the character of the sound waves sent by the ultrasound to the character of the returning sound waves, an ultrasound image is generated.

What is the difference between a Doppler and an ultrasound?

A Doppler ultrasound is a noninvasive test that can be used to estimate the blood flow through your blood vessels by bouncing high-frequency sound waves (ultrasound) off circulating red blood cells. A regular ultrasound uses sound waves to produce images, but can’t show blood flow.

What does the red and blue mean on ultrasound?

The blue and blue colours depict the direction of blood flow in relation to the ultrasound probe, whether the blood is coming towards or going away from the probe. They do not depict oxygenated or deoxygenated blood and pure or impure blood.