1. Many mothers want the ultrasound doctor to tell them the sex of the fetus, but this is not allowed in our country. The Maternal and Child Health Law clearly states that “gender identification for non-medical purposes is not allowed”. So, don’t ask this question again when you have an ultrasound. 2.Why is it best to do the ultrasound for fetal malformation screening between 20-24 weeks? Although the earlier the malformation is detected, the smaller the fetus is before that, the development is not perfect and the image is not clear enough. In addition, at this time, the amniotic fluid is relatively large and the fetus has more space to move around, so the fetus can be observed comprehensively through the change of fetal position during the short time of ultrasound. 3.Why does the ultrasound report in late pregnancy often write “XX exploration is unsatisfactory?”? The reason is that in late pregnancy, the fetus has less space to move around and is mostly in the curled position, i.e. all the limbs are curled up in front of the face and chest, which will produce obstruction. For example, the hand blocks the mouth and the leg blocks the hand. Therefore, these parts of the fetus are not satisfactory due to the fetal position, but it does not mean that there is a developmental problem. But it does not mean that there is a developmental problem. The doctor will try to explore all of them during the screening ultrasound at 20 weeks or so. 4.How to understand the limitation of ultrasound? After the ultrasound, many mothers ask, “Is my baby okay?” I hope to get a positive answer. However, doctors usually only answer, “No abnormalities were found according to the current screening standards. The current screening standard does not mean that all abnormalities must be seen. Under current medical conditions, ultrasound can detect 80% of structural abnormalities, and 20% can be missed by even the best instruments and specialists. Because ultrasound is imaging, it is limited by many factors: the clarity of the instrument, the thickness of maternal abdominal fat, the effect of maternal intestinal gas, the amount of amniotic fluid, the position and mobility of the fetus, etc. There are also some malformations that have a developmental process and are not yet evident at the time of the screening ultrasound, such as small spina bifida, diaphragmatic hernia, certain heart diseases, etc. Therefore, even if the doctor has tried his best to look at every part that should be looked at, he dare not give a guarantee to the mother. 5.What are the current ultrasound screening tests in Beijing? The first is the measurement of fetal development, including biparietal diameter, head circumference, abdominal circumference, femur length, etc., the amount of amniotic fluid, and the position and maturity of the placenta; the second is to check for hydrocephalus, anencephaly, cerebrospinal membrane bulge, severe cleft lip and palate, open spina bifida, severe heart disease, long bone loss or dysplasia of the limbs, polycystic kidney, and other malformations; in addition, the presence of gastric vesicles, bladder, and the number of umbilical vessels.