IVF, is it necessary for pregnant women to do Down's screening?

Yang Yang, a pregnant mother, doesn't know much about prenatal examination, and all the steps are carried out according to the doctor's instructions. She suffered a lot in the screening process in the Tang Dynasty. Tang screening results show that 2 1 trisomy is a high-risk group. Seeing this result, Yang Yang was almost scared silly. She can't figure it out. She is so young, her husband is in good health, and her usual living habits are also very good. Why is the fetus deformed? Yang Yang immediately called her husband to ask for leave to come to the hospital. After consulting an obstetrician, I learned that the accuracy of Tang screening is only over 60%.

The doctor advised her to do non-invasive or amniocentesis for further screening. For the next two weeks, Yang Yang didn't sleep well all day, and she was always worried about the baby's problem, which was beyond ordinary people's imagination. Finally, the non-invasive results came out, and all the indicators were low risk. I didn't expect Tang Ping to be such a liar.

Many pregnant women say that Tang Ping is cheating, and the accuracy is very low. Can you not do it during pregnancy?

Xiao Min had such a bad experience. She went for Down's screening after 16 weeks, and the results showed that NTD was high risk. A week later, I changed to another hospital for reexamination, and this time it became a high risk of OSB. Later, the doctor advised her to do non-invasive DNA. It is said that the accuracy of this test is 99%. It's been a long three weeks waiting for non-invasive results. In the meantime, Xiao Min was scared all day, and she wanted to cry at the thought of it. Her heart is heavy. Later, the results came out and everything was normal. Xiao Min said those days were like purgatory. After seeing the result, his mood suddenly brightened.

Sugar sieve is one of the main inspection items, which is cheap and quick to take effect. In many places, this kind of inspection is free and has a high penetration rate. However, it has fatal defects, the accuracy is affected by many factors, and it is prone to false positives, and the overall accuracy is only over 60%. Many people say that the accuracy of screening in the Tang Dynasty is very low. Can you not do it during pregnancy?

If expectant mothers think that the accuracy of Tang screening is low, do not want to be scared to face the high-risk results of Tang screening, or have good economic conditions, they can choose to do non-invasive DNA directly. It is also suitable for non-invasive pregnant women (over 35 years old) or IVF pregnant women. Of course, Tang sieve is not without its merits. After all, the price is low. If the expectant mother is not going to be non-invasive, Downs must do it.

Finally, I want to say that if the pregnancy test detects the high risk of Tang screening, pregnant women must not lose their minds. Please keep calm and believe that the baby is healthy.

Down syndrome screening. Down syndrome was named after John Donne, the first scientist who systematically described the disease, but it was not until nearly a hundred years later that the genetic principle was really revealed.

In short, there is a problem in the formation of sperm or egg cells, resulting in three chromosomes instead of the normal two, which can be seen under the microscope, so it is also called 2 1 trisomy syndrome. The mechanism is more complicated. Sometimes chromosome 2 1 doubles in some cells. This problem occurs in the process of cell division after fertilized eggs are formed. Sometimes, a part of chromosome 2 1 will go to other parts of the genome.

In retrospect, it seems that when I was a child, I saw more down children than now. After school, I always see them playing in the alley by themselves. It seems to have seen us. I don't know whether we are laughing or expressionless. Students call them "fools".

Later, when I learned about this disease in genetics class, I realized that Tang's son did have obvious facial and physical development characteristics, such as small fissure, upward inclination, large eye distance, bright white spots on iris, flat face and big toes. The distance is large, and the palm has unique horizontal stripes; In addition, language ability and IQ are relatively low, which is about the level of children aged 8 or 9.

In addition to IQ, 100% of Down syndrome patients have an imperfect immune system (the figures are accurate and not exaggerated) and are easily infected; Endocrine and physical development are also slow; The incidence of coronary heart disease, leukemia, thyroid diseases and other diseases is also higher than others; By the age of 60, the incidence of Alzheimer's disease can reach 50-70%.

If I have to choose the most important prenatal examination, Tang Ping is one of them.

Interpretation of Tang sieve

If I had to choose one of the most important prenatal examinations, I would choose two, one is abnormal discharge, and the other is Tang Ping, not because of the complicated procedures, but because these two can reverse the pregnancy to the greatest extent, that is, the "input-output ratio" is the highest.

Tang screening actually includes a series of inspections, and each screening itself is not enough to give a clear conclusion, so it is meaningful to combine them; Even if you add it up, you can't tell me that you are pregnant with Tang's son, but I will tell you the probability of having Tang's son.

The first one is 12 weeks of color Doppler ultrasound. Facing the screen, I almost forgot to be eliminated, only excited to see the humanoid double-headed villain for the first time. After the doctor guided us to see the motionless little man in the same photo, he suddenly turned his eyes and said, "Measure the thickness of the transparent band at the back of the neck." This value can be used as a reference to judge whether it is eiderdown, but the accuracy rate is very low and the missed detection rate is too high, so it cannot be judged by this value alone. Therefore, although our baby has passed this level, it is not very reassuring (the picture on the left is our head,

/kloc-the prenatal examination around 0/6 weeks is more complicated, which is also a problem for most people. Blood was drawn, serum was separated, the concentrations of alpha-fetoprotein (MSAFP), maternal AFP, chorionic gonadotropin (hCG) and free estriol (uE3) were determined, and the risk coefficient of Down syndrome was calculated according to gestational age and body weight. Their combination and significance are roughly like this.

In addition to Down syndrome, the combination of three marker concentrations can at least tell us the risk of 18 trisomy syndrome and neural tube malformation.

But when we measure the concentration, we can't judge whether it is high or low. There is a MoM project in the test list. This is a ratio without unit, which is the ratio of the measured value of normal pregnant women in the corresponding gestational age to the median of the measured value. The serum AFP level of pregnant women with Down syndrome is low, and the MoM is about 0.7. When hCG is high, the MoM value may be close to 3. Therefore, when you look at MoM, the relative levels of the three markers are intuitive.

Because MoM is defined as the median of normal pregnant women, the median of normal pregnant women is exactly 1. At the same time, we can see why one indicator is not enough to explain the problem. In the crowd, the detection values of the three markers are distributed in a small mountain shape, and the down mother and the non-down mother are treated equally, and there is a great overlap between them. Only by combining several items can we increase credibility.

Why are elderly women in danger?

Why do you always talk about the danger of older women? In the calculation of Wittangier probability, besides the specific values of the markers, the factors that affect these values are almost equally important. The biggest "weight" is the age of expectant mothers. With the increase of pregnant women's age, the probability of giving birth to Down's children increases obviously. Only 20 years old11450, 30 years old is not too bad. After 40, the ratio is a bit scary. In other words, 40-year-old and 30-year-old expectant mothers have the same concentration of markers. 40-year-old may be judged as high risk, and 30-year-old will be the denominator. I hope everyone will see this form and don't just think about "my age is so safe!" Even if you are 20 years old, it is not impossible to be pregnant with Tang's son! So be sure to screen.

Other related factors include weight, race, IVF, insulin-dependent diabetes, smoking and twins. It's too complicated to list a formula for everyone to calculate ... but at least you can understand why the report on Down's syndrome lists seemingly irrelevant data (the picture below is found online, and the patient information is removed, and the red box and the red letter indicate the above content. Now you should be able to understand this list. They are all high-risk groups of Down syndrome, because they all surpass the rough bars.

After blood drawing 16 weeks, I received a short message from the hospital telling me that it was "low risk". Husband commented: "Congratulations, being a mother again." . So my understanding of the last two steps only stays in books. ...

Amniocentesis and villus biopsy

As mentioned earlier, Tang Ping is a "screening", so only one probability is given; If the "screening" fails, it will enter the next stage-"diagnosis", which is the amniocentesis that most expectant mothers are afraid of. In principle, screening is an indirect examination, but in diagnosis, evidence should be obtained directly from fetal cells or DNA, or placental cells homologous to the fetus should be taken for genetic material detection.

With the help of ultrasound, amniocentesis uses a needle to penetrate the expectant mother's abdomen to reach the uterus, avoiding the baby, taking out some amniotic fluid, separating fetal cells from it, and directly seeing which chromosome is wrong. Mom's wound usually heals in a day or two.

In addition, the villus biopsy mentioned all the time is usually done earlier than the sheep puncture. Its principle is to take cells from the abdomen or along the vagina and cervix and go deep into the placenta. Because both placenta and fetus develop from the first gestational sac and have the same genetic background, that is to say, the chromosome state in placental cells can reflect whether the fetal chromosome is normal or not.