Ultrasound is a widely used ancillary test. Due to the different indications, the specific examination process is not exactly the same, nor is the preparation before the examination. Color ultrasound is used for obstetric examination as follows: 1. When used to diagnose early pregnancy within the third month of pregnancy, it is necessary to hold enough urine in the bladder before the ultrasound examination to be able to clearly see the gestational sac or fetal body in the uterine cavity; 2. No special preparation is generally required for ultrasound examination after the third month of pregnancy; 3. Advance appointment is required for 4D ultrasound examination; 4. There is no pain or other discomfort during the ultrasound examination, and pregnant women should pay attention to relax and not to be nervous; 5. When performing an abdominal ultrasound examination, pregnant women only need to fully expose the part to be examined and cooperate with the ultrasonographer’s requirements.