It takes about 20 minutes to do four-dimensional color Doppler ultrasound under various conditions. Four-dimensional color Doppler ultrasound refers to the systematic examination of the structure of the fetus from head to toe, so the examination time is longer than that of conventional ultrasound, and the appointment system is generally implemented. Systematic ultrasound examination is influenced by many factors, such as fetal position and the thickness of abdominal fat layer of pregnant women, and the examination time is different. If the fetal position is very suitable, and the abdominal fat layer of pregnant women is relatively thin, and all aspects of conditions are relatively coordinated, it may take a skilled doctor about 20 minutes.

If the fetal position is not suitable, such as when the fetal face, nose and lips need to be examined, it is difficult to observe if the fetal face is covered with both hands or the face is close to the mother's spine. At this time, pregnant women need to lie on their side, so that they can check the fetus by changing their positions. If the fetus has not turned over during the fetal examination, it is recommended that pregnant women walk for about half an hour before returning to the clinic.

If the fat layer of the abdominal wall of pregnant women is thick and the fetal structure is fuzzy, the abdominal wall can be pressurized. Nowadays, many pregnant women have a thick abdominal fat layer, so it is necessary to check the fetal position as much as possible. If you can't get a satisfactory image after several inspections on the same day, or you haven't finished checking the required structure, you can ask pregnant women to check again another day.