Ultrasound is now widely used because it is very safe, easy to perform and has low cost. Among ultrasound techniques, color Doppler ultrasound is highly appreciated, applied in examining and diagnosing many diseases in the body, especially fetal ultrasound.

Doppler ultrasound is a safe, highly accurate diagnostic imaging technique that measures the direction and speed of blood cells as they move through vessels. The movement of blood cells causes changes in the reflected sound waves, known as the Doppler effect. Doppler ultrasound can detect diseases such as carotid artery stenosis, liver and kidney disease, and the need for pregnancy screening early.