Generally speaking, after having one of the 3D ultrasound or 4D ultrasound, there is no need to continue to choose the other one. Three-dimensional ultrasound and four-dimensional ultrasound are both based on picture stereoscopic imaging, which can observe in detail the growth and development of the face, torso and internal organs of the fetus. Comparatively speaking, four-dimensional color ultrasound is based on three-dimensional stereoscopic imaging, with an additional time dimension. It can observe the facial expression of the fetus in the abdomen as well as the movement status of various organs. Both 3D and 4D can examine the fetus in detail, and can determine whether there are any growth and developmental abnormalities, such as cleft lip and palate, spinal anomalies and so on. At the same time, ultrasound has a certain degree of radiation, so it is not recommended to do it several times, so you can choose one between 3D and 4D.