Will B-ultrasound examination affect the healthy development of fetus?

B-mode ultrasound is a very useful medical diagnostic instrument, which is often used in obstetrics to diagnose pregnancy and observe the growth and development of fetus and placenta. For a long time, it is generally believed that B-ultrasound is a non-invasive and harmless examination. In fact, ultrasound is also a kind of energy. When it reaches a certain dose, it will have a biological effect in the subject, causing damage to local cells with biological effects. In most organs of the human body, it doesn't matter how many cells are damaged, but if the germ cells or embryos in the sensitive stage of development are damaged, the consequences will be serious.

Someone once used lymphocytes from umbilical cord blood of newborns for "sister chromatid exchange"

Test, referred to as SCE test, compares the SCE of umbilical cord blood of newborns who received B-ultrasound examination for the first time within 3 months of pregnancy, 4-6 months of pregnancy and 7 months to full term with those who did not receive B-ultrasound examination after pregnancy. The results showed that the frequency of SCE in umbilical cord blood of newborns with B-ultrasound in early pregnancy increased, but there was no significant difference between newborns with B-ultrasound in the middle and late pregnancy and those without B-ultrasound.

The increase of SCE is a warning signal that the body is affected by environmental harmful factors, which reflects the situation of cells that survive after the genetic material of cells is damaged. Early pregnancy is the most dangerous stage for embryos to be affected by teratogenic, mutagenic and carcinogenic factors. B-ultrasound increases the SCE frequency in this stage, suggesting that fetal DNA may be damaged in some way. Therefore, obstetric B-ultrasound examination in early pregnancy should be used with caution.

However, it is still inconclusive whether B-ultrasound will affect the fetus and how long it will take to check. In China, 10000 pregnant women received routine pregnancy examination at a dose of 20mW/cm2, and no fetal abnormalities were found. In order to further ensure safety, the safe dose of ultrasonic examination in China is 1987/0mw/cm2. Therefore, in addition to scientific research or long-term dynamic observation of the fetus under special circumstances, the routine B-ultrasound examination used in obstetrics and gynecology in hospitals at present is harmless to the fetus.