Last week the clinic gave the pregnant woman an appointment for a prenatal diagnostic ultrasound, and the pregnant woman repeatedly stressed, “I want to do the 4D. I won’t do it if it’s not 4D! There were a lot of pregnant women coming to the maternity clinic that day, and in the rush I could only explain that the ultrasound for the purpose of malformation detection, it doesn’t matter how many dimensions, the key is the qualification of the doctor doing the ultrasound. The so-called qualification is of course the identification of some kind of ability and permission to start work. The role of prenatal diagnostic ultrasound is mainly to check whether the fetus has congenital malformations and defects, which mainly relies on two-dimensional imaging to determine, especially major malformations in the two-dimensional plane diagnosis is more important. From the ultrasound doctor’s point of view there is no strict sense of four-dimensional, the exact term is “real-time three-dimensional”, that is, on the basis of three-dimensional plus the time dimension, real-time imaging, the probe sweep over, the baby frown, grin, can see the action. Sounds quite high, some hospitals will also add a headshot in the ultrasound sent to pregnant women, so that the hospital to meet the need to increase charges, pregnant women to meet the emotional needs. But there is no real medical value. In addition, in order to take a clear headshot, it may increase the time for the pregnant woman to receive the ultrasound. Prolonged ultrasound has a thermogenic effect and cavitation, which can have some potential harm to the fetus. Therefore, doctors are usually very careful not to stay in the important organs during delivery.