Registration is required on the day of the 4D. 4D ultrasound is usually performed when the pregnant woman is 20-24 weeks pregnant. The 4D ultrasound can observe the development of the fetus and whether there are any structural abnormalities of the organs, etc. The 4D ultrasound is a very important examination in the maternity checkup. Many hospitals require an appointment for this test, and registration is also required on the day of the test. On the day of the examination, you need to register first, and then go to the doctor’s office to get a checklist, and then go for the ultrasound examination. The examination takes a long time and does not require an empty stomach. If the position of the fetus is not quite right at the time of the examination, you can move around appropriately before proceeding. The results of the examination need to be submitted to the doctor for review, and if there are any abnormalities, they need to be dealt with promptly.