When the fetus is not clearly seen during the 4D ultrasound examination, it mainly refers to the fetal position and posture that affects the display of images, making the doctor’s observation of certain parts of the fetus unclear and affecting the diagnosis. When doing 4D ultrasound examination, the regular measurement and observation of the fetus can generally be carried out smoothly. 4D ultrasound is not only to carry out the regular measurement, but more importantly, to check the abnormalities of fetal development. If the fetus moves frequently during the examination of heart development, the observation of the heart and large blood vessels will be affected. If the fetus and the mother are facing each other during the examination of the fetal facial development, especially if the face is close to the placenta or the uterine wall, it will also affect the display of the facial features. If the fetus is in a fist-clenching position during the examination of the fetal fingers, it will also affect the observation of the fingers, so don’t give up the observation of these parts and let the pregnant mother take a side-lying position before the examination. If there is no change in the fetal position, just let the pregnant mother get up and take a walk and do the examination again.