4D ultrasound is an image formed through specific post-processing on the basis of traditional ultrasound, which is clearer and more accurate than traditional ultrasound. The main checks of 4D ultrasound are as follows: i. Screening for facial malformations, during the 4D ultrasound examination, observe whether the fetal eyes and orbits are equal in size and roundness, measure the eye distance, hard palate, soft palate and upper lip arcs, whether the curve is continuously interrupted, etc. Second, screening of spinal deformity, observing whether there is bulge in the spine, whether there is disorder in the arrangement, whether there is mass in the sacrococcygeal region, etc. Third, the neurological system can be examined for anencephaly, hydrocephalus, microcephaly, spina bifida and meningeal bulge. Fourth, the 4D ultrasound should also check the urinary system to detect hydronephrosis, polycystic kidney, urethral obstruction, etc. Fifth, in the fetal digestive system, it can detect intestinal bulge, visceral ectopia, intestinal atresia and megacolon, etc.