Four-dimensional ultrasound is mainly used for malformation screening, including the head, face, bones, spine, limbs and various organs, amniotic fluid and so on. Head examination can detect whether the fetus has hydrocephalus, anencephaly and other abnormalities, the face can be used to detect cleft lip and palate and other conditions, spine examination can detect whether there is spina bifida and other abnormalities, limbs, bones development is normal or not, but also can detect whether there is a fetus with abnormalities of the external ear, digestive tract and other anomalies. The time for 4D ultrasound is 20~24 weeks of pregnancy. If a pregnant woman finds any of the above abnormalities in her fetus during the examination, it is recommended that she consult a doctor in a timely manner, and under the doctor’s guidance, complete the relevant examinations to clarify the cause of the disease and provide symptomatic treatment.