What does it mean for doctors to suggest prenatal diagnosis? Prenatal diagnosis is to detect and diagnose the development of the embryo in the uterus before the fetus is born. What does it mean for doctors to suggest prenatal diagnosis? Is to check whether there is anything wrong with the fetus, which is a very important prenatal examination. Let's have a look.
What does the doctor mean by suggesting prenatal diagnosis? 1 the doctor suggested that prenatal diagnosis refers to the detection and diagnosis of the developmental state of the embryo or fetus and whether there are diseases before birth. The methods of prenatal diagnosis generally include physical diagnosis, cytogenetic diagnosis, gene diagnosis and biochemical detection.
1, Body diagnosis: Body diagnosis is to diagnose fetal congenital malformations, such as limb deformities and neurovascular defects, by B-ultrasound.
2. Cytogenetic diagnosis: Culture cells by villus sampling and cord blood sampling for prenatal diagnosis of chromosome diseases.
3. Gene diagnosis method: Using DNA probe for fetal diagnosis can diagnose many genetic diseases, such as diabetes, kidney disease and heart disease.
4. Biochemical examination: Biochemical examination can determine the enzymes, protein and their metabolites in maternal blood, fetal blood, amniotic fluid and chorionic villi, so as to diagnose various hereditary diseases, intrauterine infection and abnormal fetal growth and development.
If the fetus is diagnosed abnormally before delivery, the pregnancy will be terminated.
During pregnancy, we must pay attention to a light diet, and we need regular checkups to observe the physical condition of the fetus at any time.
What does it mean for doctors to suggest prenatal diagnosis? Prenatal diagnosis refers to the detection and diagnosis of the development of embryos or fetuses and whether there are diseases before birth. So as to seize the opportunity and choose the right time for intrauterine treatment of treatable diseases; We can make wise choices about intractable diseases. The broad prenatal diagnosis objects include: repeated spontaneous abortion in early pregnancy; History of previous birth defects; Family molecular genetic disease history; Family history of neural tube defects; Pregnancy 1 diabetes, hypertension, epilepsy, asthma; Contact with drugs, viruses and environmental hazards; Parents, close relatives
Chinese name
prenatal diagnosis
Foreign name
prenatal diagnosis
catalogue
1, history
2. Purpose
3. Objectives
4. Methodology and scope
Invasive prenatal diagnosis
Noninvasive prenatal diagnosis
history
Except for abortion in the first and second trimester of pregnancy and intrauterine death of fetus, about 3-5% of the babies born have physical structure or mental defects. In all perinatal deaths, congenital defects account for 20-25%. In the past, couples with unusually high genetic risk were usually in a passive position, and they had no choice but to give birth to healthy offspring. It was not until 1966 that scholars discovered the correlation between the elderly pregnant women and Down syndrome. Since then, prenatal diagnosis has developed rapidly.
Down syndrome (2 1 trisomy syndrome) is the most common chromosomal abnormality in live births. Therefore, prenatal diagnosis in a narrow sense is only aimed at diseases with abnormal fetal chromosome number or structure. Fetal-derived cells were obtained by invasive diagnostic methods (villus sampling, amniocentesis and percutaneous umbilical vein puncture) during pregnancy, so as to detect, find and diagnose the karyotype, so as to terminate the pregnancy as soon as possible before delivery.
Because this diagnostic method has complications related to sampling, such as abortion, for large-scale population, screening method is used to find high-risk population first, and then invasive prenatal diagnosis is used. This strategy accords with the principle of health economics.
Prenatal screening in China was carried out relatively late, and it was not until 1998 that foreign databases and risk value calculation software were gradually introduced. In 2002, China formally formulated the Administrative Measures for Prenatal Diagnosis Technology, and various localities successively approved the establishment of prenatal diagnosis institutions, gradually standardized the serological screening of 2 1 trisomy and 18 trisomy and neural tube defects in the second trimester, and carried out prenatal diagnosis.
purpose
The purpose of prenatal diagnosis is not limited to finding abnormalities before birth to terminate pregnancy. In fact, prenatal diagnosis includes the following purposes:
1, so that doctors can seize the appropriate opportunity to treat the fetus or newborn after prenatal diagnosis with drugs or surgery before or after delivery.
2. Parents can know the pregnancy status and then make wise choices.
3. After parents are informed, they have the opportunity to prepare psychologically, socially, economically, and medically to face possible health problems in utero or newborns.
target
Based on the Technical Standard for Cytogenetic Prenatal Diagnosis of Fetal Chromosome Abnormality issued by the Ministry of Health of China on 20 10, as far as cytogenetics is concerned, the indications for prenatal diagnosis include:1elderly pregnant women over 0.35 years old; 2. Prenatal screening of high-risk pregnant women with fetal chromosomal abnormalities; 3. Pregnant women who have given birth to children with chromosomal diseases; 4. Prenatal ultrasound examination of pregnant women suspected of fetal chromosomal abnormalities; 5. One of the spouses is a chromosome abnormality carrier; 6. Other circumstances that the doctor thinks it is necessary to make prenatal diagnosis. [ 1]
In addition, prenatal diagnosis in a broad sense should also include: repeated spontaneous abortion in early pregnancy; History of previous birth defects; Family molecular genetic disease history; Family history of neural tube defects; Pregnancy 1 diabetes, hypertension, epilepsy, asthma; Contact with drugs, viruses and environmental hazards; Parents, close relatives
Method and scope
Invasive prenatal diagnosis
Amniocentesis (amniocentesis)
It is mainly used for prenatal diagnosis of chromosomal abnormalities. At 16-22 weeks, amniotic fluid 10-20ml was extracted under ultrasound guidance. Because amniotic fluid is rich in fetal exfoliated cells, it can be used for the detection of the following items.
1) Down syndrome (2 1 trisomy)
Also known as congenital idiot, that is, the number of chromosome 2 1 is not normal 2, but 3. The reason is that one of the parents of the child, in the process of germ cell formation, because chromosome 2 1 does not separate, abnormal gametes combine with normal gametes, resulting in meiosis. Because the probability of elderly women over 35 years old increases obviously with age, it is considered as one of the indications of prenatal diagnosis.
Typical symptoms include severe mental retardation, small head, low muscle tone, and specific facial features (wide eye distance, oblique outer canthus, epicanthus, low nasal root, frequent mouth opening, tongue sticking out and drooling). Ear position is low or abnormal. The occipital bone is flat, the waist is bun, the neck is short and wide, and the neck is webbed. The maxillary development is poor, and the palatal arch is high, short and narrow. Congenital heart disease (most common is ventricular septal defect). The hand is short and wide, and the fifth finger bends radially. Specific skin texture.
2) 18 trisomy (Edward's syndrome)
Most of them are produced by meiosis of parental germ cells, and there is no separation. The manifestations are: slow growth and development before and after birth, low birth weight, poor sucking ability, difficult feeding, mental retardation, small and long head and occipital protuberance. Wide eye distance and epicanthus. Nose up, ears down. The neck is short and the skin is slack. 90% were complicated with congenital heart disease (ventricular septal defect, patent ductus arteriosus, etc.). ). Small chin. Infants have low muscle tone and then move more. Vulvar malformation (male cryptorchidism, female clitoris and labia majora dysplasia, perineum abnormality)
The prognosis is very poor, 95% of them miscarried in the fetal period, and13 children died within one month after birth. 50% died two months after birth.
3) Turner syndrome.
Also known as congenital ovarian hypoplasia syndrome and female gonadal hypoplasia. There is one less X chromosome than normal women, which leads to related clinical symptoms, including primary amenorrhea, webbed neck, cubitus valgus and short stature.
4) Detecting intrauterine infection (such as cytomegalovirus, cytomegalovirus), and determining whether there is fetal infection through virus culture and amniotic fluid PCR detection. )
5) Decompression in case of hydramnios. [2]
Cashmere sampling
In the early pregnancy, under the guidance of ultrasound, a small amount of villi was extracted through vagina or abdomen. Because chorionic villus is composed of fetal cells with outer trophoblast, compared with amniocentesis in the second trimester, its advantage is that if chromosome abnormalities are found in early pregnancy screening, such as Down syndrome (2 1) and Edward syndrome (18), etc. CVS can be used for early detection and diagnosis. On the one hand, it can greatly relieve the pressure of pregnant women; On the other hand, if it is necessary to terminate the pregnancy, the harm is less.
The disadvantage of this method is that the risk of surgery-related abortion is relatively high, reaching 2-3%. In addition, if it is performed before the ninth week of pregnancy, limb abnormalities may occur. So it is usually done after 1 1 week.
Other problems include maternal cell contamination.
But at this time, neural tube defects and other structural abnormalities cannot be diagnosed.
Percutaneous umbilical vein puncture
Besides diagnosing chromosomal abnormalities, it can also be used to treat Rh alloimmune hemolysis.
4. Preimplantation genetic diagnosis.
5. Fetal endoscopy [3]
Noninvasive prenatal diagnosis
ultrasound
It can be used to evaluate gestational age, determine the sex of intrauterine pregnancy, locate placenta, determine multiple pregnancies, and find structural abnormalities related to chromosome, metabolism and molecular inheritance.
Rapid prenatal diagnosis
Because of the traditional fetal karyotype analysis, it takes 7- 10 days to harvest and analyze the metaphase cells. The workflow is complicated, which requires certain qualifications of staff, so it takes a long time from sampling to reporting. At present, the industry standard of China's Ministry of Health requires that the report be issued within 28 working days, which brings great trouble to pregnant women and their families who are waiting for the results, and they are in a state of anxiety for a long time, so rapid prenatal diagnosis emerges as the times require. [4]
Rapid prenatal diagnosis does not require culture. For interphase fetal cells, the operation and film reading process are relatively simple, which greatly shortens the reporting time. But at present, the commonly used methods include:
Technology based on fluorescence in situ hybridization
fish
Primer in situ labeling technique (PRINS)
Comparative genomic hybridization
Spectral Karyotype Analysis (Sky)
Microarray comparative genomic hybridization
Technology based on PCR
real time pcr
Multiplex ligation-dependent probe amplification (MLPA)
Digital PCR technology (digital PCR) [5]
What does the doctor mean by suggesting prenatal diagnosis? What should I check for prenatal diagnosis?
Prenatal diagnosis is mainly to check the following contents: including chromosome diseases, such as Down syndrome; Sex-linked genetic diseases, such as red-green color blindness; Inherited metabolic defects, such as phenylketonuria; Congenital malformation, such as congenital heart disease.
Prenatal diagnosis methods are generally divided into two categories according to different materials and examination methods, namely, traumatic methods and non-traumatic methods. The former mainly includes amniocentesis, villus sampling, cord blood sampling, fetal mirror and embryo biopsy. The latter includes pre-implantation diagnosis, maternal serum screening and ultrasound diagnosis, DNA isolation diagnosis and so on. At present, prenatal diagnosis is still mainly based on traumatic methods, and amniocentesis and villus sampling are the two most commonly used methods.
Who is the target of prenatal diagnosis?
1, pregnant women over 35 years old;
2. Prenatal screening of high-risk pregnant women with fetal chromosomal abnormalities;
3. Pregnant women who have given birth to children with chromosomal diseases;
4. Prenatal B-ultrasound examination for pregnant women who suspect that the fetus may have chromosomal abnormalities;
5. One of the spouses is a chromosome abnormality carrier;
6, doctors think it is necessary to other circumstances of prenatal diagnosis.
After the introduction of this article, I believe you already know something about prenatal diagnosis. Generally, the doctor will inform the prenatal diagnosis when the prenatal screening is abnormal. So if there is no problem with prenatal screening, there is no need to ask for it, because prenatal diagnosis is traumatic and will have a certain impact on the fetus.