Large-scale rejection was performed at 24-28 weeks of pregnancy, and fetal malformation was ruled out by high-resolution color Doppler flow imaging.

Routine items: fetal position, biparietal diameter, occipital frontal diameter, abdominal diameter, femur length, incus length, amniotic fluid, fetal movement, fetal heart, placenta position, placenta thickness, placenta classification and placenta lower edge.

Nine screening items for large-scale abnormalities: cerebellum, upper lip, gastric vesicle, four chambers of heart, kidney, bladder, tibia, fibula, ulna, radius, spine and abdominal wall.

At present, most hospitals have 3D/4D color Doppler ultrasound for large-scale ultrasound. Four-dimensional color Doppler ultrasound is not necessary for the examination of large row malformation, and three-dimensional color Doppler ultrasound and two-dimensional color Doppler ultrasound can also be used for detection.

However, at present, four-dimensional color ultrasound is the most advanced color ultrasound equipment in the world. "4D" is the abbreviation of "4D". The fourth dimension refers to the vector of time, so it is also called real-time 3D. It provides a wide range of applications, including abdomen, blood vessels, small organs, obstetrics, gynecology, urology, newborns and pediatrics. It can display the real-time dynamic image of the fetus intuitively and stereoscopically, and understand the movement process of the fetus in the uterus. The dynamic video recording of fetal intrauterine state can also be kept as a permanent memorial.

Therefore, most pregnant mothers will choose four-dimensional color Doppler ultrasound during large-scale abnormal examination.