Why is the early stage of Tang screening during pregnancy always a high risk?

Hello, I'm glad to answer your question. Down's screening is only a screening in prenatal examination, the accuracy rate is only 60-70%, and it cannot be used as the final diagnosis. Even if Tang screening finds high risk, there is still the possibility of anti-screening.

There are many reasons for the high risk of Tang screening, such as virus infection, radiation, blind medication and so on. If Tang screen indicates high risk, amniocentesis can be performed again to make a final diagnosis. If you are worried about the risk of puncture, you can also choose non-invasive genetic testing, but screening alone is not a diagnosis.

Tang sieve is a hormone in the blood of pregnant mothers, which is calculated by formula based on gestational age and weight, so I want to tell you that the test results are easily influenced by various factors, so the accuracy is not high.

I hope my answer can help you!

Down's screening is high risk, especially the word high risk. I often see pregnant women asking me with a high-risk list. Now I will explain to you the most puzzling aspect of Down's screening.

1. Why does Down's screening become a high risk because all the previous prenatal examinations are normal? Down's screening is a detection method for 13 trisomy, 18 trisomy and 2 1 trisomy syndrome. Generally, it can be between 1 1 and 14 weeks (recommended by Europe and America) or between 16 and 20 weeks (China routine). Down's screening in China is about 16 weeks, and blood is drawn to check alpha-fetoprotein, free chorionic gonadotropin and free estriol. The proportion is calculated by software. At present, the machine setting value of domestic hospitals is generally 1:270, and exceeding this value is a high risk. If only one of the three indicators exceeds the standard, most of them will become high risk. Even if all prenatal examinations before Down's screening are normal, these three examinations may be abnormal, which may lead to high risk.

2. What about Sister Tang's high risk? In high-risk cases, according to the national guidelines, prenatal diagnosis is recommended, and the specific measures are as follows:

1. Chorionic puncture: 1 1 to 14 weeks. If it is found before 16 weeks, it is ok. /kloc-Don't do Down's screening after 0/6 weeks.

2. Amniocentesis: recommended 16-20 weeks. If there is a high risk of Down's screening, you can do it at this time. Amniocentesis has a certain risk of abortion, and the probability of abortion is about 1%.

3. Umbilical cord blood puncture: Generally, it can be done after 24 weeks, but now many hospitals stop doing it after 32 weeks.

3. Will Down's high-risk fetus have it, and will it give birth to deformed children? It can be said that the risk of Down's screening is high, and prenatal diagnosis is recommended. If there is no chromosome abnormality, it is completely possible, and the probability of fetal malformation can be reduced to one in ten thousand. So even if Down's risk is high, the probability of fetal malformation is very low, so don't worry too much.

Conclusion: The high risk of Down's screening is detected by blood sampling index, and one abnormality will lead to high risk, so prenatal diagnosis is needed to judge whether there is fetal chromosome abnormality.

Although the overall accuracy of Tang screening needs to be improved, the accuracy of early Tang screening is still acceptable and not always high-risk.

How did the risk of screening in the early Tang Dynasty come from? Firstly, it must be based on the values of β-hcg and pregnancy-related plasma protein A, and secondly, it must be combined with maternal age, weight and gestational age. Here, maternal age is a very important factor, accounting for a large proportion. If there is something wrong with this embryo, the risk of Tang screening is naturally there. Secondly, generally speaking, the older you are, the higher the risk is.

Is the early Tang sieve worth doing? I look at this problem this way. If the pregnant mother is young, has no relevant family history, has no previous history of adverse induced labor, and has no other high-risk factors, screening in the early Tang Dynasty can also be used as the first choice. I have to admit that the price advantage of early Tang screen is obvious.

Considering only the accuracy, what is the best choice?

Tang Zaosi is definitely not always taking risks. If there are always risks, we must find the problem, even if we find a solution. Risk value of Down's screening The theoretical basis of Down's screening is that the hormones secreted by abnormal fetuses are abnormal compared with those of normal fetuses, and combined with the risk of comprehensive evaluation of pregnant women's age and fetal gestational age, five people who are farthest from the normal level are selected as high risk. It is considered that these five people have a high risk of chromosome abnormality.

Therefore, in Down's screening, 5 out of every 100 people are doomed to be at high risk, because that's how our experimental threshold is taken. So the high-risk ratio is 5%, and most of them are low-risk. So not most of them are high-risk, which loses the significance of inspection.

For another example, we randomly find out 100 men of the same age, and think that the shortest five of these 100 people are "abnormal", and we think that these five people have growth defects of stunting. But in fact, two of these five people may be normal short stature and have no developmental defects, which is a "misdiagnosis". Of the 95 people who are considered normal, there may be 3 people with developmental defects, which is a missed diagnosis. In fact, most tests determine the diagnostic threshold in a similar way, so missed diagnosis and misdiagnosis are objective.

Therefore, the high risk of Down's screening only means that the risk of illness is high (about 10% is problematic, and 90% is misdiagnosed normally), while the low risk of Down's screening only means that the risk of illness is low, not that there is no risk (about 20%-30% missed diagnosis).

Tang screening was conducted during pregnancy, and the test result was high risk. In order to confirm whether the baby in the belly is really a child with Down's syndrome, the doctor suggested that Dong Er should have amniocentesis for diagnosis.

Dong Er was pregnant for the first time. When she and her husband met such a situation, they immediately panicked.

Dong Er hurriedly called the leader for leave, still crying. After listening to her description, the leader began to comfort her: "Don't panic, I am also at high risk, but don't you think my son is very healthy?" Qu Jie from the Administration Department and Tang Jie from the Finance Department. At that time, Tang Si Er was at high risk, and all the children born were healthy. "

Dong Er listened to the leader's comfort and began to calm down slowly, and his mind returned to reason.

Through all aspects of understanding and learning, and consulting a doctor, Dong Er went to do a non-invasive DNA test, and the final result was low risk, with an insurance policy attached. If Down's baby is born, the insurance company will pay a certain fee, and the couple will be relieved.

It was not until they gave birth to a healthy daughter that Dong Er and her husband were completely at ease.

Correct understanding of Down's screening results;

Why is the result of Tang sieve always high risk? The increase of some special substances in maternal serum from fetus and placenta indicates that the fetus is at risk of Down syndrome. These substances include alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG), estriol (uE3), PAPP-A and inhibin A.

Down's screening is to extract pregnant women's serum, then extract the concentrations of alpha-fetoprotein, human chorionic gonadotropin and free estriol, and then calculate the probability of Down's syndrome in the fetus in combination with the gestational age, weight and age of the pregnant mother.

① gestational age

The calculation of gestational age is usually not so accurate, which will affect the results of Down's screening.

Many pregnant mothers don't know the specific date of their pregnancy, so they will calculate it according to the first day of the last normal menstruation, which requires that the menstrual cycle of pregnant mothers is regular, assuming that you will ovulate on 14 days after the first day of menstrual cramps.

There are also some pregnant mothers who can't determine the date of their last normal menstruation, or the menstrual cycle is irregular, which can be inferred from the first B-ultrasound, but it is not absolutely accurate.

② Weight

Overweight pregnant mothers will affect the results of Down's screening.

Some people can't control their weight too low, and some people gain too much weight during pregnancy.

In modern society, when conditions are good, many pregnant mothers only want to increase nutrition and neglect weight control in order to give birth to a healthy and intelligent baby, which will lead to excessive weight gain and affect the test results.

③ Age

In modern society, many women are older when they are pregnant. The older you get, the higher the risk of comprehensive calculation.

Hospitals no longer recommend Down's screening for pregnant women over the age of 35.

Due to various pressures, some women are not young when they are pregnant, and some have entered the ranks of elderly women.

Pregnant mothers in their thirties and forties are also common. Some time ago, a 67-year-old pregnant woman gave birth to triplets.

④ Multiple births

The content of these substances in the serum of pregnant women with multiple pregnancies is high, so the test results are unreliable.

Let's see what netizens say: Netizen 1: We don't do Tang screening here now, and hospitals do non-invasive treatment for pregnant women with local household registration for free.

Netizen 2: When I was pregnant with Dabao, the ignorant were fearless. I don't make a sieve at all. When I was pregnant, Tang Sie was in critical condition. After discussing with my family, I said I'd better be non-invasive and spend money to buy peace of mind. Now that the children are healthy, I am satisfied. Nothing is more important than health.

The netizen gave birth to a second child at 3:36. The doctor directly said that don couldn't pass the screening. Amniocentesis is the safest and can't afford to gamble. There is no hesitation immediately, and the probability may be lower. The result of sheep piercing is obvious. Now Bauer is two and a half years old, lively and lovely. She must listen to the doctor's advice during pregnancy, because the consequences can't be borne.

Netizen 4: I wanted to be non-invasive when I was pregnant, but because I had received blood donation before pregnancy, it would not be very accurate, but the doctor refused to approve sheep puncture because of low platelets, so I had to go back and think for myself. It was so tangled.

Starhouse parenting: If the pregnant mother is suitable, you can consider doing non-invasive DNA or amniocentesis, and the accuracy is more guaranteed.

Now the prenatal examination is very correct. Early screening during pregnancy is risky. Personal advice pays more attention.

Although you don't have to believe it completely, many people say that this is only a temporary indicator. But I will be very careful what I say, and I will carefully let the ship sail forever.

Being pregnant is a big responsibility. In the attitude of being responsible for the baby, the doctor asked me not to take any tests.

Early screening during pregnancy is risky, so follow the doctor's advice and let you do whatever you want. Make sure you're okay and at ease.

After all, it is worthwhile for the baby.

Many pregnant mothers know that Tang screening should be done in the second trimester, but few pregnant mothers know that Tang screening is actually divided into early Tang and middle Tang. According to what you said, the initial inspection of Tang sieve should refer to the early Tang Dynasty.

Early Tang Can is usually examined in 12 weeks. Before I got pregnant, Tang had an early nt, and the result was low risk. But as far as I know, many people are as high-risk as the subject said, but the result of non-invasive screening in the early Tang Dynasty is low-risk. What is the reason?

1. Factors affecting the results of Tang screening. First of all, if you are a pregnant woman over 35 years old or a pregnant mother with multiple births, the result of Tang screening is very likely to be high-risk, influenced by age and number of births.

Secondly, if the pregnant mother has improper diet or insufficient rest for a long time before screening in the early Tang Dynasty, it may also affect the examination results, which is the influence of the pregnant mother's own physical condition factors.

Finally, because the results of Tang sieve are not 100% accurate, sometimes there are some deviations due to the interference of medical equipment, and there are high-risk situations, which are affected by medical equipment factors.

2. My suggestion. First of all, pregnant mothers should control their diet reasonably, give priority to light food, avoid eating too much spicy and fried things, eat more fruits and vegetables, and adjust their physical condition before making Tang sieve.

Second, pregnant mothers need to ensure adequate sleep and avoid excessive fatigue.

Third, pregnant mothers should not worry too much if the screening test results in the early Tang Dynasty show high risk. Most of them have done non-invasive DNA.

To sum up, during pregnancy, pregnant mothers are really prone to anxiety and fear because of unsatisfactory test results. In fact, these so-called prenatal projects are probabilistic, which means that there may be errors, so pregnant mothers don't have to worry too much. If there is a problem, do further tests.

Before Down's screening, the pregnant mother was in 12 weeks. Now NT is whether the NT index of the fetus will exceed 3.0. If it exceeds 3.0, it needs to be rechecked. By 16 weeks, pregnant mothers began to do Down's screening, which is also a means to check Down's syndrome. However, Down's screening often presents high risks, and many pregnant mothers feel weak every time they see this word. If the baby is deformed and the fetus is not born well, the deformity is difficult to cure. Many pregnant mothers don't know that the accuracy of Down's screening is only 60%-70%, so if the test result is high-risk, then pregnant mothers should not be too anxious.

How to check the results of Down's screening: Doctors combine the concentrations of fetal protein A and human chorionic gonadotropin in pregnant women's blood with pregnant women's weight, gestational age, expected date of delivery and other indicators, and then calculate the risk coefficient of Down's syndrome in the fetus through equipment.

However, many pregnant mothers have abnormal weight fluctuations, and the gestational age is not allowed. The gestational age is not allowed to be a heart or menstrual disorder, and the ovulation period is impermanent, which will naturally affect the results of Down's screening. Therefore, when pregnant mothers see high risks, don't worry too much. Maybe it's just because they've gained weight, or the gestational age is wrong.

What should I do when the pregnant mother's Down's screening result is high risk? The first step is to check again. If the test report is still high-risk, then non-invasive DNA or amniocentesis is needed.

Pregnant mothers can choose non-invasive DNA, and the detection of non-invasive DNA is not dangerous, just taking blood. It is very simple to draw blood from pregnant mothers and then extract fetal free DNA fragments from the blood for sequencing, with an accuracy rate of 99%.

Amniocentesis is very dangerous, and the abortion rate is 1%. The doctor will pass the B-ultrasound, then find a good needle and a good puncture position. The doctor will smear alcohol on the pregnant mother's stomach and insert a long needle into the pregnant mother's stomach. The long needle will pass through the pregnant mother's abdominal wall and reach the uterine wall. After helping pregnant mothers to extract appropriate amniotic fluid from the uterus, pregnant women will rest in bed for 2 hours.

Amniocentesis is a diagnostic technique and is considered as the gold standard of dyeing physical examination. Amniocentesis is to puncture the pregnant mother's stomach with a slender needle and then extract amniotic fluid from the pregnant mother's uterus, which may cause the pregnant mother's amniotic fluid to flow out and bleed, and may also hurt the baby, especially after 24 weeks. The risk of doing amniocentesis is greatly increased.

As long as amniocentesis is done, the results of the examination are chromosome abnormality, chromosome deletion and duplication, which may be improved with the evolution of the fetus, but pregnant mothers should still consider whether to keep their children and make a decision in time, so that it is not easy to induce labor when the fetus is older, and it is also very harmful to pregnant mothers.

The full name of Down's syndrome screening test is "Down's syndrome screening test", which is to take the peripheral blood of pregnant women, detect the concentrations of fetal protein A, HCGb and free estriol, and then calculate a risk value by computer in combination with the weight, gestational age and expected date of delivery of pregnant women.

However, today's young people are under great pressure. They have to get married, buy a house, buy a car, have children and face the problem of work. Therefore, women are getting older and older, and many older women join the ranks of having a second child. Therefore, the high-risk ratio of Tang sieve has been improved in this way.

The main inspection items of Tang Sieve are 2 1- trisomy, 18- trisomy and 13- trisomy, among which the accuracy of 2 1- trisomy is high and the other two are poor. Early and middle Tang dynasties were screened. 1 1 ~ 13 weeks +6 in the early Tang dynasty and 16 ~ 20 weeks in the middle Tang dynasty.

The results of Tang sieve inspection are divided into three categories: low risk, critical risk and high risk. The low risk indicates that the probability of Down syndrome is low. Non-invasive DNA is generally recommended for pregnant women in critical risk, and puncture is generally recommended for pregnant women in high risk

If the risk of early Tang Dynasty is high, chorionic puncture can be done at 1 1 ~ 13+6; If the risk of mid-Tang is high, amniocentesis can be done in 16 ~ 20 weeks; If late B-ultrasound suspects fetal chromosome abnormality, cord blood puncture can also be done at 24 ~ 32 weeks.

The above picture shows puncture, which has a risk of infection or abortion of about 3‰. Generally, puncture diagnosis is recommended only when the risk of Tang screening is high, or the risk of trauma is not high, or abnormal fetal development may occur in the late stage of B-ultrasound.

Generally speaking, Tang screening is just screening, not prenatal diagnosis. The overall accuracy of Tang sieve is not high (only about 60%~70%), and the positive prediction rate is even lower (about 3%). Therefore, in the future, Tang sieve is likely to be replaced by non-invasive DNA.

In short, pregnant women need not worry too much if they are screened for high risk. Because the positive predictive rate of Tang screening is only 3%, that is to say, in the same period 100 test results, only 3 times are real Down syndrome after amniocentesis.

The function of Down's screening during pregnancy is to find fetal abnormalities as early as possible, so as to make an appointment for amniocentesis earlier (18-22 weeks). If some mid-Tang dynasties are almost 20 weeks old, it is often impossible to make an appointment for amniocentesis. Some people even need to do more dangerous cord blood puncture.

Back to the topic, why is Down's screening always high-risk in early pregnancy? This is essentially related to this technology, so I won't go into details. Both the mid-Tang period and the early Tang Dou period have the shortcomings of low detection rate. Therefore, it is necessary to expand the early-Tang+mid-Tang joint screening and early-Tang+mid-Tang +NT joint screening to improve the detection rate.

In fact, my personal suggestion is to allow non-invasive DNA testing as much as possible. Non-invasive DNA examination usually takes 12-22 weeks, and only 2 1, 18 and 13 chromosomes are examined, but most of them are abnormal chromosomes, especially 2 1- trisomy, accounting for more than half.

To sum up, the positive rate of Down's screening during pregnancy is high, and the detection rate is low. It is suggested to do non-invasive DNA testing directly if possible. Good luck with your pregnancy.