Jiang Yulin, chief physician of Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, provided answers from two aspects.
On the one hand, regarding why prenatal screening is necessary, Jiang Yulin stated that prenatal screening is the screening of fetuses for congenital defects and genetic diseases at the appropriate gestational age through methods such as ultrasound and blood tests. Prenatal screening can detect common fetal chromosomal diseases, such as Down syndrome, as well as the vast majority of serious and fatal fetal structural abnormalities, such as open spina bifida, severe congenital heart disease, and obvious short limbs. This is also why it is repeatedly emphasized that expectant mothers should undergo standardized prenatal screening, as it is indeed very important and can effectively reduce fetal birth defects and ensure maternal and infant health.
On the other hand, scientifically speaking, under current scientific and technological conditions, prenatal screening cannot detect all defects in the fetus, mainly due to the following two reasons:
One limitation is the technology itself, such as ultrasound examination, which is achieved through ultrasound imaging with limited resolution and can only detect relatively large structural abnormalities. For some very small structural abnormalities, such as small ventricular septal defects and abnormal numbers of fingers and toes, it is indeed difficult to detect them clearly during pregnancy. Moreover, ultrasound can also be affected by many factors, such as the mother's thick abdominal fat, abnormal amniotic fluid volume, or fetal position obstructing the examination site, which may affect the results of the examination.
The second is that there are various types of birth defects, and current prenatal screening can only target some common birth defects. For some rare deformities or genetic metabolic diseases, it is not within the scope of routine screening. At present, it is also difficult to detect through ordinary screening, and science and technology are indeed in the process of development.
