The main purpose of the gross examination is to check whether there is any abnormality in the development of various systems of the fetus, and if there is any abnormality in the development, it may be necessary to terminate the pregnancy. It is a very important test performed in the middle of pregnancy between 18 and 24 weeks. It is performed by means of 3D ultrasound or 4D ultrasound to see if there are any abnormalities in the appearance of the fetus’ limbs, spine and other organs. It can also be used to estimate the week of gestation, assess the size of the fetus, and determine the orientation of the fetus. It can also screen for chromosomal abnormalities. The ultrasound examination needs to be operated by professional doctors in specialized hospitals. Before the examination, try to let the fetus be in a more active situation, so that it can be better observed.