With the popularity of eugenic knowledge, prevent deformity of children with mental retardation Chi Daier birth, many couples to have become one of the issues of most concern. The development of modern medical science has been able to check the unborn fetus of pregnant women in order to diagnose the fetus is healthy or abnormal, decided the fate of the fetus. Check the amniotic fluid is such a very effective method of prenatal diagnosis.
Check more in the amniotic fluid after 16 weeks
Mrs. Chen, 36, is already an advanced maternal age, the doctor told her that pregnant women over the age of 35 years old, suffering from Down syndrome and other fetal chromosomal abnormalities significantly increase the likelihood of the disease, suggested that I go to the hospital after 16 weeks of pregnancy to do the amniotic fluid Check. She was surprised, why wait until 16 weeks later? Earlier inspection, earlier know the result, not better? Doctor smiled and said: "Even if only two to three weeks ahead of time to do amniocentesis, fetal malformation or risk the possibility of causing a miscarriage will be greatly increased. While it is not fully explain why, but there is a possibility that, amniotic fluid reduction will lead to umbilical cord entanglement, and this time the umbilical cord has only one line like thickness, thereby endangering the blood supply to the fetus. "
Genetic counseling before checking the amniotic fluid
Amniotic fluid is fetal growth and development of the environment. Fetus in the uterus, floating in the amniotic fluid, metabolic activity of many lives through the amniotic fluid, so check the amniotic fluid and exfoliated cells of fetal amniotic fluid, which can reflect the physiological and pathological fetuses. Since 1967 the world's first successful application of amniocentesis, cells from the amniotic fluid loss has been detected chromosomal abnormalities in amniotic fluid technology has broad and in-depth examination of the development.
Check more in the amniotic fluid of pregnant women during pregnancy, 16-20 weeks, through amniocentesis, amniotic fluid taken for inspections include cell culture, identification of sex chromatin, karyotype analysis, determination of amniotic fluid alpha-fetoprotein, amniotic fluid, biochemical tests, etc. to determine the degree of maturity and health of the fetus, diagnosis of fetal abnormalities, or with certain genetic disease. Yunfu during the amniotic fluid before the test, often first through genetic counseling, when the estimated risk of baby had just Jinxing exception.
The formation and composition of amniotic fluid
That the formation of amniotic fluid in early pregnancy, when the amniotic fluid mainly from the maternal blood of dialysis material, some from fetal plasma. 4 months pregnant, the fetus's urine mixed with amniotic fluid, amniotic fluid decreased the concentration of solute, sodium decreased. Term, the fetal urine into the amniotic fluid, making the amniotic fluid and fetal plasma osmolality lower than the mother. With the progress of gestational age, amniotic fluid volume also increased. 7 months of pregnancy when the amniotic fluid volume up to 1000 ml, and later gradually reduced to a full-term pregnancy is about 500-800 ml of amniotic fluid, and amniotic fluid during pregnancy expired and was significantly reduced.
Under normal physiological conditions, amniotic fluid and rapid updates, is generally believed that amniotic fluid will be updated once every 3 hours, the physiological metabolism in fetal amniotic fluid plays a very important role.
The formation mechanism from the amniotic fluid can be seen, the composition of amniotic fluid in early pregnancy with the mother when the same plasma, but low protein content. With the progress of gestational age, derived from the gradual accumulation of fetal lung phospholipids in the amniotic fluid. Amniotic fluid of 98-99% water, 1-2% of the solute. Amniotic fluid also contains glucose, fat and organic matter. Medical tests on the amniotic fluid often some elements to understand the health of the fetus. The fetus in amniotic fluid throughout pregnancy in comfort through.
What circumstances need to do amniocentesis
Amniotic fluid contains fetal skin samples, and other organs of the cell, before being tested in the laboratory will be placed on training. Two weeks after the results came out. In most cases, only the status of fetal chromosomes. Although aspects of amniocentesis in the detection of chromosome almost 100% accuracy rate, but it can not detect a similar structural abnormalities or heart disease. Carrying genetic diseases such as Tay family idiot, cystic fibrosis and sickle cell and other couples to be more targeted to accept amniocentesis.
Amniocentesis is mainly used for detection of various birth-related diseases, and genetic disorders for over 35 years old, 15 to 18 weeks of pregnancy expectant mothers. If you have a genetic disease or chromosomal abnormalities such as family history, or abnormal fetal ultrasound and other tests, the doctor will advise you to amniocentesis. Some mothers mentioned above, although not the case, but in order to eliminate concerns, would require amniocentesis. Amniocentesis cost between 400 and 3,000 yuan, according to the number of test items made, the amount is different.
1. Determination of fetal maturity
Handling high-risk pregnancy, to reduce perinatal mortality, fetal maturity to understand, combined with determination of placental function, select the favorable opportunity of giving birth.
2. Prenatal diagnosis of congenital anomalies
a. Sex-linked genetic disease carriers, to determine sex of the fetus during pregnancy
On the X-linked recessive genetic diseases, such as hemophilia, Honglvsemang, pseudo-hypertrophic muscular dystrophy family history of psychosis fetus, early identification of fetal sex, male fetuses should be aborted pregnancy.
b. Senior citizens over the age of 35, pregnant women prone to fetal chromosomal abnormalities
Mainly refers to the chromosomal (autosomal and sex chromosome) number or structural abnormalities. Usual chromosomal abnormalities have Down's syndrome (21 - c body), sex chromosome abnormalities with congenital hypoplastic ovary syndrome (45, XO) and so on.
c. Front tire for the family history of Down's syndrome or
Extracted from amniotic fluid cells in fetal DNA, a gene for analysis or directly or indirectly, to do testing. Such as diagnosis of thalassemia, phenylketonuria, muscular dystrophy and so on.
d. Pregnant women are often chromosomal abnormalities, congenital metabolic disorder, family history of enzyme system disorders
The basic cause is a mutation in the genetic code caused by a protein or enzyme abnormalities or defects. Inherited metabolic diseases related to the metabolic system, such as lipid metabolic disorders, mucopolysaccharide deposition disease, metabolic diseases of amino acids, carbohydrates and other metabolic diseases. A hexosamine enzymes, such as lack of vitality, the central nervous system caused by accumulation of lipid material Tay family dementia; due to an enzyme defect that prevents metabolism of lactose and other Erzhi galactosemia.
e. Of neural tube defects before birth or the pregnancy serum alpha-fetoprotein (AFP) was significantly higher than normal pregnancy
Amniotic fluid alpha-fetoprotein (AFP) value of 12 to 14 weeks gestation to reach the peak, then gradually decreased to almost undetectable at term. Usually 8 to 24 weeks of normal pregnancy amniotic fluid AFP is 20 ~ 48μg/ml. Open neural tube defects in brain or spinal cord exposed, often 10 times higher than normal. In addition, stillbirth, congenital esophageal atresia, duodenal atresia, omphalocele, congenital nephrotic syndrome, pregnancy and other serious Rh blood group incompatibility can also be elevated AFP values.
3. Mother suspected child blood group incompatibility
Check the amniotic fluid in blood group substances and ABO hemolytic disease of newborn bilirubin contribute to the diagnosis, prevention and treatment. If diagnosed as ABO blood group incompatibility, prenatal monitoring should be strengthened and prepared to rescue the newborn after delivery.
4. Whether fetal intrauterine infection
Rubella virus infection in pregnant women, the amniotic fluid can be measured specific immunoglobulin. Such as interleukin -6 in amniotic fluid increases, there may be subclinical intrauterine infection can cause miscarriage or premature delivery.
What do potential risk of amniocentesis
Amniocentesis procedure is generally safe, although there is cause maternal injury, damage the fetus, placenta and umbilical cord, amniotic fluid leakage, abortion or premature delivery, intrauterine infection risk, but no more than 1 / 200.
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