When a pregnant woman goes to the hospital for a prenatal checkup, sometimes the doctor will tell her to undergo an amniocentesis procedure. However, due to the high cost of the procedure and the concern that it may affect the health of the fetus, it is not recommended. Do pregnant women need to undergo amniocentesis? Which pregnant women can have amniocentesis? Amniocentesis is a diagnostic procedure that uses fetal shed cells, chorionic villus cells or fetal blood cell cultures in amniotic fluid to diagnose fetal chromosomal disorders and sex determination of surname chain genetic disorders. This procedure is generally used for prenatal diagnosis in mid-term pregnancies (16-22 weeks of pregnancy). Amniocentesis is a more common means of prenatal diagnosis, but it is not necessary for every pregnant woman. In general, patients with the following conditions need to undergo amniocentesis: 1. Pregnant women who have been infected with viruses such as rubella during pregnancy. 2. Pregnant women who are consanguineous. 3.Pregnant women of advanced age: Pregnant women aged 35 years or older. As the age of the pregnant woman increases, the risk of having a child with chromosomal abnormalities also increases. 4.Pregnant women with a family history of sex-linked genetic disorders. The chance of having a child with a sex-linked genetic disorder is about 25% if the mother is a carrier of a gene for a severe sex-linked disorder or a sex-linked disorder. 5. Pregnant women who have given birth to children with multiple congenital malformations; pregnant women who have given birth to anencephalic children or spina bifida developed neural tube malformation; the chance of having a child with the disease in the next pregnancy is about 5%. The best time for amniocentesis is: 1. 16 weeks to 22 weeks of pregnancy. Because the volume of amniotic fluid is appropriate at this stage and the activity of fetal decidual cells in amniotic fluid is still available, it is easy to culture successfully for karyotype analysis. 2.The process of amniocentesis is explained in detail. Before the official extraction of amniotic fluid, the doctor will do an ultrasound examination for the pregnant woman to determine the size of the fetus, the number of weeks of pregnancy, the position of the fetus and the number of fetuses. 3. Find the most suitable location for the needle; disinfect the skin of the pregnant woman; spread a sterile sheet on the belly of the pregnant woman; use a 20 or 22 gauge spinal puncture needle to gradually pierce the previously selected amniotic cavity under the guidance of ultrasound; make sure the spinal puncture needle is already in the amniotic cavity and start to draw out the amniotic fluid with negative pressure, about 20 ml of amniotic fluid (the first 2 ml of amniotic fluid must be discarded to avoid maternal cell contamination ); place the inner tube of the puncture needle back; draw back the whole puncture needle; put a bandage on the needle hole of the belly; amniotic fluid examination is completed! 4, after the amniotic fluid examination is completed, the pregnant woman needs to sit outside and rest for about 10 minutes, if there is no discomfort, she can go home. Risks of amniocentesis: Amniocentesis is an invasive test for pregnant women. Although most amniocentesis is safe, the following may occur: 1. There is a small risk of miscarriage, with a probability of about 1 in 250. 2. Complications occur in pregnant women, often some of the following: leakage of amniotic fluid from the puncture eye, requiring re-closure; uterine spasmodic contractions; mild or severe bleeding. 3. Although there is a risk of causing maternal injury, damage to the fetus, placenta and umbilical cord, amniotic fluid leakage, miscarriage or preterm delivery, and intrauterine infection, the ratio does not exceed 1/200, so the mother-to-be does not need to worry about safety. What tests can be done with the amniotic fluid obtained by amniocentesis? 1.Fetal cells in amniotic fluid can be used to diagnose whether the fetus has chromosomal disorders. 2.Measure the level of AFP in amniotic fluid to diagnose whether the fetus has neural tube abnormality, abdominal cleft and other malformations. 3.The fetal cells in the amniotic fluid can be used to analyze the sex of the fetus and applied to pregnant women with concomitant chromosomal genetic disorders to decide on the fetal trade-off. 4.Determination of lecithin and sphingomyelin content in amniotic fluid. 5.To determine the blood type of the fetus with amniotic fluid to prevent mother-child blood group disagreement. 6.Do enzyme analysis and various measurements on fetal cells in amniotic fluid to diagnose whether the fetus is suffering from metabolic diseases. 7.To determine the content of creatinine, enzymes, proteins and hormones in the amniotic fluid to provide indicators for the diagnosis of fetal diseases. 8.Check whether there is infection in the amniotic cavity. Does the normal result obtained from amniotic fluid analysis guarantee a normal fetus? In the diagnosis of fetal chromosomal abnormalities, the accuracy of the amniocentesis test method can reach 99.4% to 100%. When will the results be available after amniocentesis? It usually takes 2 weeks for the analysis of fetal chromosomes and a few days for the determination of metanephrines.