Whether 3D ultrasound can be passed at one time is related to the condition of the fetus, if the development of the fetus is normal, it can be passed at one time, there is no way to artificially control whether it can be passed or not. Do three-dimensional ultrasound belongs to a kind of ultrasound, not only can observe whether the fetal development is abnormal or not, but also can check the situation of the placenta, amniotic fluid and umbilical cord. Three-dimensional ultrasound to detect fetal malformations, mainly around 22-26 weeks of pregnancy. You can make an appointment at a regular hospital according to your schedule. When conducting the examination if the amniotic fluid in front of the fetus’ face is too small, the fetus is close to the uterus and placenta, and the mother is too fat, etc., which can not be completely shown clearly, it will lead to the 3-D not being able to pass at one time. Some pregnant women can be examined successfully after moving around and adjusting the posture, etc., which can expose the fetus that can not be shown, but some may still not be examined, and they need to be rechecked again in a couple of days.