Today there are more and more people who seek perfection, the perfect object, the perfect marriage, the perfect family, and of course, the perfect healthy baby. Many women start running to big hospitals from the moment they know they are pregnant, not only because they have the best doctors and the most exquisite medical technology, but also because they have the most experienced ultrasound doctors. Parents-to-be must know that there is a very important test in mid-pregnancy, and that is the ultrasound screening for fetal macromastia from 20 to 24 weeks of pregnancy. How much do you know about this important test? 1.When is the fetal macromasound screening done? How many times will it be done? If the fetus is too early, the fetus is too small for the ultrasonographer to observe, and if the fetus is found to be seriously malformed too late, the termination of pregnancy by live birth will bring ethical problems. In our hospital, the screening of large malformations by fetal ultrasound is only scheduled once in the middle pregnancy, and the routine ultrasound examination in the late pregnancy will observe whether there are abnormalities such as hydrocephalus, hydrothorax and ascites, dilated intestine and dilated renal pelvis. 2.Is ultrasound screening for large fetal malformations a panacea? Most pregnant women come to large hospitals to do fetal macromasound screening, they often think that doing this test is the same as the baby all normal, no more problems, like buying an insurance policy, everything is peaceful, waiting for the melon to ripen. I do not know: fetal malformation ultrasound screening is not a panacea, but not to do is never! Due to the limitations of science and technology and the individual differences of pregnant women, some pregnant women have thicker abdominal walls and poorer sound transmission, so ultrasound screening can only detect about 60%-70% of structural abnormalities. The current ultrasound screening items for fetal macromas include: cranial halo, lateral ventricle, cerebellum, posterior cranial fossa pool, spine, cervical soft tissue, orbit, mouth and lips, four-chamber heart, chest, gastric vesicle, intestinal canal, both kidneys, bladder, both upper limbs humerus and ulnar radius, both lower limbs femur and tibiofibula, both wrists, both ankles, umbilical vessels, a total of 23 items. The main reasons for misdiagnosis and omission are as follows: (1) Fetal structure is a gradual formation and dynamic development process, fetal malformation also has a development process, sometimes there is no absolute clear boundary between normal and abnormal, malformation may not be revealed by ultrasound when it has not developed to a certain extent. For example, bone dysplasia cannot be detected in time in the middle of pregnancy. For example, the fetal growth indicators are within the normal range during the ultrasound screening at 22 weeks of gestation, but during the ultrasound examination of obstetric fetal growth measurement at 32 weeks of gestation, it is found that the fetal biparietal diameter, head circumference and abdominal circumference are normal, but the femur and humerus are only equivalent to the level of 26 weeks of gestation, and there is dysplasia of long bones. This is a situation that cannot be anticipated by ultrasound screening for large anomalies, and ultimately, termination of pregnancy by induction of labor is the only option. Some transient anomalies such as ventricular dilatation and choroidal cysts may disappear during follow-up. Other disorders such as small brain bulges can occur irregularly and may be sporadic on ultrasound. Still other delayed disorders such as cerebral liquefaction due to intrauterine infections often manifest late in pregnancy. (2) Due to the physiological characteristics of the fetus itself, the diagnosis of some diseases is very difficult. For example, complex cardiac malformations may be missed or misdiagnosed in the fetal period because of the difficulty in diagnosis. In addition, some small malformations or abnormalities cannot be included in the screening scope yet due to the difficulty of examination, such as auricular malformation, palm and toe malformation, invisible spina bifida, etc. (3) Many malformations have great variability in clinical presentation. For example, congenital hydrocephalus and hydronephrosis have only mild manifestations during fetal life and may manifest as severe disease after birth or may gradually improve. (4) About 60% of chromosomal diseases have no ultrasound manifestation, so most chromosomal diseases cannot be detected by ultrasound, let alone diagnosed by ultrasound, and require serological or amniotic fluid aspiration chromosome examination. 3.How many times is the ultrasound screening of fetal macrosomia completed? Why some large bellies can finish the examination quickly, while some need to be examined repeatedly several times? Friends who have come to the ultrasound department can often see some big bellies going in and out repeatedly for multiple examinations, with anxious faces and nervous looks, and some even doing strange and difficult movements on the soft leather-backed chairs in the ultrasound department. That’s right! These are the pregnant women who came for ultrasound screening of fetal macrosomia! Why does the above situation occur? This is because of the position of the baby inside the uterus. Some lucky pregnant women, the position of the fetus with the doctor’s examination, all the front, back, left and right structures can be seen at once, then congratulations she can pass the screening once and for all! However such lucky ones tend to be very few, only about 1/3 of them, and most of them need more than two times, and some even need to come back for another examination on another day. During this period, it requires the cooperation of the pregnant woman to eat some high-calorie food or drink to give the baby sufficient energy to move inside the uterus, and to change the position and then let the ultrasonographer check again to ensure that all the mandatory items can be observed, which is a bit tougher. Some breech babies are even more “painful”, breech babies are more difficult to observe the spine, often requiring the pregnant woman to maintain the chest and knee position for 10-20 minutes, so that the fetus in the uterus hip elevation or change to the head position to facilitate observation of the fetal spine. This is the reason why those big bellies are in the chair in a concave position.4 After doing the fetal macrosomia ultrasound screening, how do the results look? Regardless of whether the test results are normal or not, the report card should be shown to the doctor in the obstetrics clinic because the doctor’s eyes are often not only concerned with fetal structure, but also with fetal size, placental position, amniotic fluid volume, etc. The ultrasonographer will only give advice on the fetal problems, for example, in the unfortunate event that a fetal abnormality or anomaly is found, sometimes the ultrasound report will be accompanied by a recommendation for further fetal high-risk ultrasound, fetal heart ultrasound or a multidisciplinary consultation on the prognosis of the fetus. In conclusion, as doctors, we will do our best to carefully examine each fetus to obtain more information and screen for more fetal diseases. All mothers and family members should understand the importance and necessity of ultrasound screening for fetal macrosomia and cooperate fully with the doctors. For you and your baby, let’s work together!