You do not need to go on an empty stomach for a 4D. 4D usually refers to four-dimensional ultrasound, a type of gynecological ultrasound, is one of the methods used by women to screen for fetal structural malformations during pregnancy and does not require an empty stomach. With 4D ultrasound, it is possible to visualize the fetus for intrinsic and extrinsic malformations, as well as fetal facial and limb development. Congenital heart disease, abdominal wall defects, defects on the outer edges of the limbs, congenital spina bifida, anencephaly, cleft lip and palate can be observed and judged under 4D ultrasound. Four-dimensional ultrasound is usually good at 24-28 weeks of pregnancy, which is the time when the fetus is formed, the amniotic fluid volume is moderate, the fetus is of the right size, and the images are clearer. This kind of examination does not need empty stomach, you can eat some light liquid food that is easy to digest before the examination, and drink a moderate amount of water to facilitate the examination.