Tang Ping sent a text message.

Yangyang, 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, Yangyang was almost scared silly. She can't figure it out. She is so young, her husband is in good health, and she usually has good living habits. Why is the fetus deformed? Yangyang immediately called her husband to ask for leave to come to the hospital. After consulting an obstetrician, I learned that the accuracy of Down's screening is only over 60%.

The doctor advised her to do non-invasive or amniocentesis for further screening. In the next two weeks, Yang Yang didn't sleep well every day. She was always worried about the baby, 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. After 16 weeks, she went for Down's screening, and the results showed that the risk of NTD was high. 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%. Waiting for the results of non-invasive examination has been a long three weeks. 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 became clear.

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, its accuracy is affected by many factors, and it is prone to false positives, and its 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 the expectant mother thinks that the accuracy of Tang Screening is low, does not want to face the high-risk results of Tang Screening in fear, or has good economic conditions, she 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. Downs must do this if the expectant mother is not going to be non-invasive.

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

Down syndrome screening. Down syndrome was named after John Tang, 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 chromosomes, 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 enter other parts of the genome.

Looking back now, it seems that I saw more Down's children when I was a child 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, big toe and other toes. The distance is large, and the palm has a unique horizontal pattern; In addition, the language ability and IQ are relatively low, about the level of 8-year-old or 9-year-old children.

Except IQ, 100% of Down syndrome patients have imperfect immune system (accurate figures, no exaggeration) 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 had to choose the most important prenatal examination, one of them would be Tang Screen.

Interpretation of Tang sieve

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

Tang sieve actually includes a series of inspections, each of which is not enough to give a clear conclusion, so it is meaningful to combine them; Even if you add it up, you can't say that you are pregnant with Tang's son, but I will give you the probability of being pregnant with 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 same motionless little man as the 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 a down's syndrome, but the accuracy rate is very low and the missed detection rate is too high, so it can't be judged only by this value. Therefore, although our baby has passed this level, it is still not very reassuring (the picture on the left is our head,

/kloc-The check-up around 0/6 weeks is complicated, which is also the trouble of most people. Blood was drawn, serum was separated, the concentrations of alpha-fetoprotein (MSAFP), maternal serum 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, that is, the ratio of the measured value of normal pregnant women in the corresponding gestational age to the median of the measured value. The level of serum alpha-fetoprotein in pregnant women with Down syndrome is low, with MoM of 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 the definition of MoM is 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 mothers and non-down mothers 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 say that older women are dangerous? In the calculation of Waitangi 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 baby increases obviously. 20 years old is only11450, and 30 years old is not too bad. After the age of 40, this ratio is a bit scary. In other words, 40-year-old and 30-year-old expectant mothers measure the same concentration of markers, and 40-year-old may be judged as high risk, while 30-year-old will be the denominator. I hope everyone can see this form and don't just think, "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, there is really no way to list a formula for everyone to calculate ... but at least you can understand why the report on Down syndrome lists seemingly irrelevant data (the following picture was found online, the patient information was deleted, and the red box and red letters 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 exceed the rough standard.

0/6 weeks after blood drawing/kloc-,I received a short message from the hospital, telling me that it was "low risk". Husband commented: "Congratulations, being a mother again." . So my experience in the next two steps only stays in books. ...

Amniocentesis and villus biopsy

As mentioned earlier, Tang Ping is a "screening", so only a 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 the inside, and directly checking which chromosome is wrong. Mom's wounds usually heal in a day or two.

In addition, the villus biopsy mentioned all the time is usually performed earlier than the sheep puncture. Its principle is to get cells from abdomen or along vagina and cervix and go deep into placenta. Because both placenta and fetus develop from the first gestational sac, they 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.