Objective To preliminarily investigate the role and significance of ultrasonography in prenatal screening and diagnosis. Methods The results of 7469 fetal malformation screening and 972 high-risk fetal ultrasound were retrospectively analyzed. Ultrasound examination was performed by segmental examination method, and a total of 19 items were examined in detail for each fetal organ and organ. 1.Wide scan of the abdomen of pregnant women to understand the fetal position, number of fetuses and the presence of fetal heartbeat. 2.Section scan of fetal body parts: (1) Fetal head: measure the width of lateral ventricle, biparietal diameter and head circumference in the biparietal plane; measure the transverse cerebellar diameter, posterior cranial fossa pool width and cervical soft tissue thickness in the cerebellar plane; observe the integrity of the cranial halo. (2) Fetal face: observe bilateral orbits, bilateral nostrils and upper lip continuity. (3) Fetal chest: observe the heart and both lungs and other thoracic structures. The heart requires observation of the four-chambered heart view, left ventricular outflow tract and right ventricular outflow tract; (4) Fetal abdomen: observe the continuity of the abdominal wall, intestinal echo, gastric alveoli, both kidneys (including renal pelvis), bladder, umbilical vessels at the umbilical port, and measure the abdominal circumference; (5) Fetal extremities: observe the composition of the femur, tibia-fibula, humerus and ulnar radius bones bilaterally, measure the length of the femur and humerus, and observe the ankle and wrist joints bilaterally. (6) Fetal spine: observe the morphology of the spine in three longitudinal, transverse and coronal sections, the composition structure and the integrity of the surface skin. 3.Final observation of placenta, amniotic fluid, umbilical cord and other structures, and measurement of amniotic fluid depth or index. 4.When the observation site cannot be shown due to the change of fetal position during the screening examination, let the pregnant woman move around and then perform the examination again. For the part that cannot be observed because it finally cannot be shown clearly after 2 repeated examinations, make an appointment to recheck within 1 week. 5.For pregnant women with inappropriate menstrual cycles and fetuses smaller than the screening gestational week, reschedule the ultrasound screening date after measuring the fetal size and recalculating the gestational week. 6. For pregnant women with fetuses larger than 24 weeks of gestation, they will be included in the ultrasound of high-risk fetuses, and try to obtain comprehensive imaging and examination, and also conduct detailed examination according to the above ultrasound screening content. 7. For other high-risk fetuses, add key observations according to their high-risk factors.