3D ultrasound is a common examination tool in obstetrics and gynecology, mainly used to check fetal development, placenta, umbilical cord and amniotic fluid during pregnancy, and mainly used to check whether the placenta is completely expelled and uterine regeneration after delivery, in addition, it can also be used to check uterine adnexa, heart and breast etc. 1. fetal development: 3D ultrasound can understand fetal growth and development more clearly. Usually, 3D ultrasound is done during the 24th-32nd weeks of pregnancy. At this stage, the fetal organs are developing and the length and weight of the fetus are changing. It can also observe the blood flow resistance index of the fetus through the blood flow signal and judge whether the fetus is safe in the uterus; 2. placenta: through 3D ultrasound, we can observe whether there is any abnormality in the form and position of the placenta, such as whether there is placental abnormality, placenta previa, placenta abruptio, etc., which can be detected and taken measures in time to avoid adverse effects on the pregnant woman and the fetus; 3. umbilical cord: through 3D ultrasound, we can observe the changes of the umbilical cord, such as Whether the umbilical cord is straight, bent or wrapped around the neck, etc., can be detected and corrective measures can be taken in time; 4.Amniotic fluid: through the amniotic fluid index in 3D ultrasound, the amount of amniotic fluid can be roughly calculated to determine whether there is too much amniotic fluid or too little amniotic fluid, etc., and decide whether intervention is needed in combination with the fetal development; 5.Uterine adnexa: through this examination, it can be observed whether there are abnormalities in the function and structure of the uterine adnexa. abnormalities. It is also possible to observe the postpartum uterine regeneration. If there is incomplete uterine regeneration, uterine contraction agents such as uterine contraction agents need to be given in time for treatment to promote uterine recovery. It can also see the size and shape of the uterus, whether there are deformities or hyperplasia, and whether there is an intrauterine device, the position of the device, and also observe whether there are uterine adhesions, uterine fibroids, uterine polyps and other diseases. In addition, three-dimensional ultrasound can also check the size of the heart and blood flow, and can be used in obstetrics to check whether there are heart problems in the fetus. In addition to its use in obstetrics, 3D ultrasound can also observe the breast more effectively and examine some breast tissue lesions. It can also perform examinations related to the prostate gland, such as the size of the prostate gland, whether the density in the prostate gland is uniform, and whether there are hard nodes and calcifications in the prostate gland.