A. Why should prenatal screening and diagnosis be carried out?
There are about 1 million children born with birth defects in China every year, accounting for nearly 5% of the birth population, hundreds of thousands of children born with deformities visible to the naked eye every year, and the total number of children with congenital disabilities is as high as ten million (plus defects that become apparent only months and years after birth)
The direct economic loss caused by neural tube abnormalities in China is more than 200 million yuan per year, the treatment cost of congenital stupidity is more than 2 billion yuan, and the treatment cost of congenital heart disease is up to 12 billion yuan. The current situation of birth defects in China is not only a serious public health problem, but has become a social problem that affects our economic development and people’s normal life. The purpose of prenatal screening and diagnosis is to reduce the birth of children with disabilities and improve the quality of the population.
Second, what is genetic counseling?
Definition: A professional or consulting physician engaged in medical genetics will answer the questions raised by the consultant on the causes, mode of inheritance, diagnosis, prognosis, recurrence risk rate, prevention and treatment of hereditary diseases in the family, and make suggestions and specific guidance for reference on the issue of marriage and childbirth raised by the consultant.
Third, who should have genetic counseling?
Couples who have lived together for two years without using contraception and have not become pregnant;
The female partner is over 35 years old, and the male partner is over 40 years old;
Those who have a history of unexplained miscarriage, stillbirth or stillbirth;
Those who have chromosomal abnormalities in their own or family;
Those who have had maternal and child blood type incompatibility;
Those who have had too much or too little amniotic fluid this time or last time;
Pregnant women who have been exposed to a large number of toxic and harmful environmental factors, or who are suffering from severe viral infections;
Those whose doctors think they should be consulted and diagnosed prenatally
In fact, there is no need for consultation, in theory, every pregnant woman needs to participate in genetic screening!
What is genetic screening?
Genetic screening is the detection of genes responsible for genetic diseases or susceptibility genes in the population. In recent years, with the development of individualized medicine, genetic screening also includes the detection of genetic polymorphisms to evaluate the correlation with certain diseases and the responsiveness to certain drugs. At present, many countries and regions have established screening methods mainly for certain genetic diseases that have a high incidence, are serious or can be prevented at an early stage. Depending on the purpose and target of screening, genetic screening can be divided into carrier screening, prenatal screening, neonatal screening, population screening, drug-response screening, etc. The first three categories are most commonly used.
V. What are the criteria for genetic screening programs?
The screened disease should have a high prevalence in the screened population; seriously affect health;
After screening, there is a method of treatment or prevention
Screening methods should be non-invasive, easy to implement, and inexpensive
The screening method should be uniform, easy to promote, and easily accepted by the screened population;
The screened person should participate voluntarily to make an informed choice; and provide all relevant medical information and consultation services for the screened person
Sixth, what are the main types of genetic screening?
In 1999, the National Family Planning Commission has launched the “Birth Defects Intervention Project”, mainly through genetic screening to reduce the incidence of Down syndrome, congenital neural tube defects, congenital hypothyroidism, phenylketonuria, thalassemia, G6PD deficiency and other diseases or disability and death rates, to fully protect the safety of mothers and children and improve the quality of our population. The quality of our population. In practice, more screening for Down’s syndrome (trisomy 21), neural tube abnormality and Edward’s syndrome (trisomy 18) is carried out.
VII. What is prenatal screening?
Prenatal screening is an economical, simple and non-invasive method to identify pregnant women at risk for certain congenital defects in order to further clarify the diagnosis and minimize the birth rate of abnormal fetuses.
Prenatal screening generally includes: serology + ultrasound morphology
Serologic screening: It is usually done through the detection of maternal serum markers to identify pregnant women at risk for certain congenital defects and is therefore also called maternal serologic prenatal screening.
Usually, serologic screening during pregnancy can screen for 60 to 70 percent of children with Down syndrome and 85 to 90 percent of neural tube defects. Prenatal serologic screening is a minimally invasive test that requires only 3 to 5 ml of maternal blood and is not harmful to either the mother or the fetus.
Ultrasound screening: Ultrasound imaging is used to detect morphological and structural abnormalities. Currently, ultrasound prenatal screening focuses on six major categories of severe structural abnormalities as defined by the Ministry of Health: anencephaly, severe brain bulge, severe open spina bifida, severe chest and abdominal wall defects with internal exostosis, single-chambered heart, and lethal chondrodysplasia. Pregnant women found to be at high risk during screening should undergo further relevant tests called prenatal diagnosis.
Eight, pregnant women and their families need to know a few issues
Prenatal diagnosis is based on the principle of voluntary participation, and medical personnel will guide you to carry out prenatal care. There may be false positives and false negatives, and for the final diagnosis of high-risk pregnant women, amniocentesis and amniotic fluid chromosome examination are required.
2. Pregnant women with high risk screening indicate a high possibility of having a Down’s child, but it is not a confirmed diagnosis and prenatal diagnosis is recommended.
Pregnant women with low risk screening indicate that the possibility of having a child with Down’s syndrome is low, but the possibility of having a child with Down’s syndrome cannot be completely ruled out.
Ultrasound is recommended for those who suspect neural tube defects.
9. What is prenatal diagnosis?
Also known as intrauterine diagnosis, it refers to the diagnosis of intrauterine infection and birth defects before the birth of the fetus, including immunological diagnosis, imaging diagnosis, cytogenetic diagnosis and genetic diagnosis. Prenatal diagnosis is an effective and reliable measure to prevent the birth of fetuses with serious hereditary diseases or congenital defects, making it one of the important guarantees for eugenics and improving the quality of the population.
Unlike prenatal screening, it is more technically demanding, and the diseases to be diagnosed are complex. Therefore, it is not possible to require everyone to do as screening, only suitable for some high-risk rate of pregnant women, is targeted for a certain diagnostic procedures and experiments.
Ten, the object of prenatal diagnosis (who needs to do prenatal diagnosis?)
(1) Pregnant women who have a chromosomal abnormality (number or structure) or who have given birth to a child with a chromosomal disorder, especially a carrier with a normal phenotype and a chromosomal abnormality.
(2) Pregnant women in which one of the spouses has a monogenic disease or has given birth to a child with a single monogenic disease.
(3) Couples in which one of the couple has a neural tube abnormality or has given birth to a child with a neural tube abnormality.
(4) Pregnant women with a history of unexplained spontaneous abortion, malformation, stillbirth or neonatal death.
(5) Pregnant women with excessive amniotic fluid.
(6) Couples with a history of exposure to environmental teratogens and pregnant women with a history of active TORCH infection.
(7) Pregnant women older than 35 years of age.
(8) Pregnant women with chromosomal breakage syndrome family line.
(9) Pregnant women with a family history of genetic disorders who are consanguineous
(10) Pregnant women with high risk of prenatal screening
(11) The model of prenatal diagnosis service system and the classification of medical institutions related to prenatal diagnosis.
Establish effective referral relationships between institutions, quality control and information management systems.
Prenatal diagnosis institutions (qualified institutions)
Prenatal screening institutions (general general hospitals and maternal and child health institutions)
General maternal health institutions (township health centers. Community)
Prenatal diagnosis institutions (qualified institutions) must obtain “two certificates”, the necessary conditions to obtain the qualification to practice: institutions Personnel, prenatal screening institutions (general general hospitals and maternal and child health institutions. The Institute: can carry out prenatal screening, but does not have the ability to diagnose
General maternal health institutions (township health centers. Community) can only identify high-risk, not allowed to carry out prenatal screening.
XII. What are the diagnostic techniques for prenatal diagnosis?
Mainly (1) ultrasound diagnosis (2) interventional means amniocentesis, chorionic villus biopsy, umbilical vein puncture, fetal microscopy, (3) pre-implantation genetic diagnosis
XIII. Can all fetal abnormalities be detected after prenatal diagnosis?
It is important for the applicant couple to understand that prenatal screening or testing does not guarantee that the fetus will be born normal, and that not all pregnant women can undergo prenatal diagnosis at any gestational period. Genetic screening and screening methods are limited to high-risk pregnancies, and couples must understand that their fetus may be at risk for a genetic disorder that is only potentially detectable.
XIV. Ultrasound prenatal screening and diagnosis
Ultrasound is now widely used for prenatal diagnosis and screening. Ultrasound prenatal screening focuses on the six major categories of serious structural malformations as defined by the Ministry of Health: anencephaly, severe brain expansion, severe open spina bifida, severe chest and abdominal wall defects visceral exostosis, single-chambered heart, and lethal chondrodysplasia. Prenatal diagnosis is much more, including but not limited to fetal dysplasia or abnormalities, cleft lip (commonly known as hare lip), severe congenital heart disease, abnormal or absent organ development, limb malformation or absence, etc