3D real-time ultrasound not only has all the functions of 2D ultrasound, but also has its special functions of stereoscopic imaging, image cutting, image rotation and high plane image analysis. It can observe the activity and shape of the fetus in the uterine cavity through dynamic three-dimensional technology, and can detect infant malformations at an early stage. 3D ultrasound realizes three-dimensional imaging of local tissues and organs of the human body, and can be used for volume scanning of abdomen and small organs to accurately measure local tissues and organs, such as by examining the skin of the back of the neck of the fetus and measuring the thickness of subcutaneous tissues, which can detect hereditary (chromosomal) abnormalities during 9-13 weeks of pregnancy. The prominent feature of 3D ultrasound is that it can capture local stereoscopic images of fetal growth and development in the uterus at different gestational weeks, and the left ear and small fist of the sleeping fetus in the uterus as well as the vivid and distinct facial expressions can be clearly seen in the 3D picture.