Prenatal examination is a compulsory course for every pregnant mother, and ultrasound examination is an important part of the prenatal examination. As gestational age increases, the content of ultrasound testing is also constantly changing. So, when should you have an ultrasound? What should I pay attention to during each inspection?
Today, I will explain to you the common sense you should know about ultrasound during pregnancy.
1. Does ultrasound examination have any impact on the fetus?
The reason why people think that ultrasound may be harmful to the fetus and pregnancy is that most people equate ultrasound with X-ray , CT and other imaging examinations that contain electromagnetic radiation . In fact, ultrasound is a branch of acoustics. The applied ultrasonic waves are physical mechanical waves, not radiation. They are formed by sound being transmitted to certain substances and then forming echoes. The instrument then receives different echoes and processes them with computers to form an image. It is a sound wave that people cannot hear, and there are no reports of harmful biological effects.
2. How many ultrasound examinations are needed during pregnancy?
During pregnancy, it is a valuable method to judge the development status of the fetus through ultrasound. When pregnant women do ultrasound, they will see some numerical values and ultrasound imaging on the examination report. These numerical values and imaging tell you about the fetus. Whether the development status is normal.
Under normal circumstances, there will be about 7 ultrasounds during the entire pregnancy. However, if the ultrasound shows relative abnormalities, or other results during the prenatal checkup show abnormalities, the doctor will increase the number based on the actual clinical situation.
The first early pregnancy ultrasound (6-8 weeks after menopause)
is mainly to determine whether it is an intrauterine pregnancy and to determine whether there is a single pregnancy or multiple fetuses.
Whether it is a urine pregnancy test or HCG detection in the blood, it can only help us diagnose early pregnancy , but to confirm pregnancy, ultrasound needs to see the gestational sac in the uterus and yolk sac or fetal bud .
Just through blood or urine testing, it cannot help us rule out abnormalities such as embryonic dysplasia or ectopic pregnancy . You can also use CRL (length from fetal head to buttocks) to determine gestational age and estimate the expected date of delivery.
Monochorionic monoamniotic sac singleton
Fetal NT examination (11-13+6 weeks)
After the pregnancy is diagnosed, most mothers are excited about having a baby, but slowly develop more worries. Will there be any abnormalities in the baby, will there be any malformations... So between 11 weeks and 13+6 weeks of pregnancy, we will have a fetal NT ultrasound examination.
is mainly used to measure the thickness of NT, screen for early fetal structural abnormalities, which may be able to detect some serious fetal structural abnormalities, measure the intravenous duct spectrum and re-verify the gestational age (NT value thickening fetal chromosomal abnormality risk; Increased risk of congenital heart disease )
Fetal NT measurement
16 weeks of pregnancy
Do a routine ultrasound (level II prenatal ultrasound) to initially screen for anencephaly, severe encephalocele, and severe openness Spina bifida, severe thoracoabdominal wall defects, visceral exstrophy, single-chamber heart, etc.
Major abnormality (20-24 weeks)
After early prenatal examination, mothers in the second trimester face another big test. This is the "legendary" four-dimensional color ultrasound performed between 5 and 6 months of pregnancy. At this time, we need to perform fetal level III system ultrasound examination and fetal heart ultrasound screening. It is a systematic screening of the fetal anatomy, which can exclude most fetal malformations. It is the most important examination in the prenatal ultrasound examination of the fetus. This examination needs to see a lot of content, so the examination takes a long time, and is affected by the interference of pregnant women's abdominal wall fat, amniotic fluid , and fetal position, so the image quality will vary, and if fetal position is not good, pregnant mothers need to exercise moderately. Check again when the fetal position changes. Pregnant mothers should be mentally and physically prepared.
Minimal abnormality (28-30 weeks)
As the fetus develops, another minor abnormality is performed to screen for late-onset fetal malformations, such as hydrothoracic and abdominal hydrops, hydrocephalus, etc. At the same time, evaluate the growth and development of the fetus, observe whether the growth and development of the fetus is consistent with the gestational age, and also pay attention to whether the conditions of , placenta, and amniotic fluid are normal, as well as the S/D ratio of umbilical cord blood flow, which can reflect the fetal umbilical cord blood flow. Is the supply normal?
General prenatal ultrasound examination
After continuous clearance, the next 2 or 3 ultrasound examinations will require general ultrasound examination. It is a level I prenatal ultrasound examination. It mainly carries out fetal biological measurements, assessment of fetal position, fetal size, Amniotic fluid volume, placental position and maturity, umbilical artery blood flow parameters, etc. provide clinical basis for fetal assessment.
3. Can any fetal malformation be detected?
Ultrasound examination belongs to the category of imaging . The principle of acoustics determines that ultrasound images may have certain artifacts and artifacts. The examination is affected by various factors, including the thickness of the abdominal wall of pregnant women, surgical scars, etc., which can lead to ultrasound attenuation and poor image quality; In polyhydramnios and , the fetus moves frequently, and the fetus is too far away from the probe, making it difficult to obtain a standard section; in oligohydramnios, there is a lack of amniotic fluid as a sound-transmitting window, and the occlusion of bone sound shadows and many other factors make it more difficult to display fetal structures. Many organs or parts may not be displayed or cannot be displayed clearly, and it is difficult to display all the structures of the fetus. Prenatal ultrasound examination can detect most fetal malformations, but the diagnostic accuracy rate cannot reach 100%.
4. It is clearly said to be color ultrasound , but why do you see that most of the images are black and white?
The "color" in "color ultrasound" is the abbreviation of "color Doppler". It is an ultrasound imaging technology that adds more colors. With Pule's blood flow imaging function, color Doppler ultrasound will not be full-screen like the color TV at home. Color will only appear where there is blood flow.
Umbilical cord color blood flow diagram
5. What do two-dimensional, three-dimensional and four-dimensional mean?
Two-dimensional ultrasound is the basis of inspection. When we perform ultrasonic inspection, we basically use two-dimensional images. Three-dimensional and four-dimensional technologies perform imaging on the basis of two-dimensional ultrasound and are an auxiliary to two-dimensional ultrasound technology. More diagnostic information can be provided when needed. Let me emphasize to everyone that prenatal ultrasound examinations of the fetus are divided into level I, II, III, and IV examinations. General and routine ultrasound examinations mainly performed in the early and late pregnancy belong to level I and II prenatal ultrasound examinations. During the second trimester, large abnormalities are detected. Level III ultrasound examination is required, which is also called fetal system screening and fetal heart screening. Everyone must know which level of examination they are doing, and do not just go to the kilodimensional color ultrasound that is written. Level IV prenatal ultrasound examination is suitable for pregnant mothers who find or suspect fetal abnormalities during prenatal screening, as well as pregnant mothers with high-risk factors.
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