The purpose of prenatal ultrasound diagnosis of fetal defects is first to detect fetal development and second to rule out fetal malformations. As a high-tech device, 4D ultrasound has an acquisition speed of 35 volume data/second, which allows easier direct access to the ultrasonographer’s area of interest and allows real-time dynamic depiction of fetal movements, providing a good means of observing fetal facial and body movements and providing a superior method for detecting abnormal fetal behavior. Ultrasound multi-sectional display is useful for detecting all fetal abnormalities and it is important for localizing specific sections of organs. This is necessary for precise measurement or observation of asymmetries in a particular complex organ system, such as the fetal brain. In particular, when the fetal position is not conducive to obtaining the desired views during 2D ultrasound, 3D/4D (stored volume data) for multi-sectional display and rotation can generally provide the required information. The use of 4-D surface imaging modalities allows clear visualization of facial structural abnormalities or/and abnormal limb movements and provides an important advantage over 2-D imaging for the exclusion of fetal surface defects by 4-D ultrasound. 4-D surface imaging allows parents the opportunity to see a “picture” of their unborn child. For the parents, it is quite a surprise to see the 4-D image of the fetus’ face come to life like a photograph! For the sonographer, 4-D imaging can provide valuable additional clues and diagnostic basis for finding fetal abnormalities. There is no doubt that an experienced sonographer can create a stereoscopic image of an abnormal fetus through a series of two-dimensional scanning planes. However, when the examiner needs to explain the fetal abnormality to the fetal parents, interpretation by 2D ultrasound images alone can be difficult; especially in cases of fetal surface defects, such as facial abnormalities, spina bifida, abdominal wall and limb defects, etc. 4D ultrasound imaging allows the parents to see the fetal abnormality with their own eyes as easily as looking at a photograph, allowing them to be more aware of the severity of the defect. Currently, 4D ultrasound has become a powerful and effective adjunct to conventional 2D ultrasound examinations. Along with color Doppler, spectral Doppler, and energy Doppler techniques, 4D ultrasound has become part of our routine prenatal diagnosis and provides a more important diagnostic tool for detecting or ruling out fetal anomalies, especially in the increasing number of fetal congenital anomalies involving small malformations, by providing multiple display modes. The best time for 4D ultrasound examination is from 20 to 28 weeks of pregnancy, but of course, if fetal abnormalities are detected during pregnancy, fetal 4D examination can be performed at any time.