What does pregnant woman B exceed examination

summary

B ultrasound examination of pregnant women can well monitor the growth of the fetus and reduce the birth rate of malformed and defective infants. But does B ultrasound have an impact on pregnant women? Here is a detailed introduction to the impact of B ultrasound on pregnant women.

What does pregnant woman B exceed examination

First: B-ultrasound is a project of prenatal examination. Pregnant women can start to do B-ultrasound examination after 5 weeks of pregnancy. At this time, through B-ultrasound, we can observe whether the pregnancy site is normal (excluding ectopic pregnancy) and whether the embryo is alive. After the 13th week of pregnancy, B-ultrasound can clearly show the fetal skull, trunk, heart, lung, liver, spleen, stomach, kidney, bladder and other organs and limb bones. By measuring the data, we can estimate the fetal development, determine the fetal position and placental position, evaluate the placental function and choose the mode of delivery.

Second: B ultrasound uses ultrasound for examination. Ultrasound is a kind of non ionizing radiation. It is a kind of physical factor and energy, so there is a problem of safe dose. At present, clinical ultrasound can be divided into diagnostic ultrasound and therapeutic ultrasound. The power of the former is 100-1000 times lower than that of the latter. Whether B ultrasound is harmful or harmless to human body or fetus depends on the dose of ultrasound, also known as threshold safe dose. That is to say, when the dose of B-ultrasound used in obstetrics is less than this value, it is harmless; otherwise, when it is greater than this value, it may produce harmful effects or damage. In terms of dose, therapeutic ultrasound has certain damage or influence on human body, while diagnostic B-ultrasound will not cause damage to human body or fetus if the power of ultrasonic instrument is less than 10 MW / cm2 under the operation of doctors or technicians with strict professional training in regular hospitals.

Third: the principle of minimum dose should be adhered to in B-ultrasound examination. The minimum radiation intensity and the shortest time should be used as far as possible to obtain the necessary diagnostic data. The time for a single examination (the time for the probe to contact the abdomen) should be less than 5 minutes; the power of the ultrasonic instrument should be less than 10 MW / cm2 (the manufacturer has generally determined this safety threshold when leaving the factory).

matters needing attention

Early pregnancy (especially before 8 weeks of gestation) is a critical period for the formation of fetal organs, and it is also an important period that easily leads to fetal malformation. It is usually not suitable for B-ultrasound examination (except for special circumstances). Generally, it is more appropriate to do B-ultrasound examination in 10-13 weeks of pregnancy.