Patient's question:
Can it be done?Doctor's answer:
Hello: The best time for amniocentesis in prenatal diagnosis is around weeks 16 to 20 of pregnancy. Amniocentesis is a procedure where a small amount of amniotic fluid, produced during pregnancy, is extracted using a simple instrument under sterile conditions and analyzed to assess the health and stability of the fetus. This disappointing procedure is best performed during pregnancy. Too early, there may not be enough amniotic fluid, making it difficult to obtain a sufficient sample, which can be poor and easily injure the fetus. Too late, the fetus has already developed fully. If abnormalities are found at this stage, even if it is not suitable for continuing the pregnancy, a termination of pregnancy surgery may need to be performed. The procedure becomes more difficult and increases the risk to the mother at this time. Amniocentesis is a particularly important method for prenatal diagnosis and is generally suitable for mid-pregnancy prenatal diagnosis. Amniotic fluid exists in the amniotic cavity. The fertilized egg forms the amniotic cavity on the seventh day after fertilization, and the patient begins to produce amniotic fluid. At week 16, the volume of amniotic fluid is about 300 mL, at week 18 it is about 500 mL, and at week 20 it is about 800 mL. Near the due date, the volume of amniotic fluid slightly decreases. The best time for amniocentesis to extract amniotic fluid for prenatal diagnosis is unclear, as it is around weeks 16 to 20. At this time, the fetus is small, and there is relatively more amniotic fluid. The fetus floats in the amniotic fluid, surrounded by a relatively wide band of amniotic fluid, making it less likely to injure the fetus when extracting 10 mL of amniotic fluid, which only accounts for 1/10 to 1/20 of the total volume. It will not cause the uterus to suddenly shrink and lead to miscarriage. During this period, the proportion of viable cells in the amniotic fluid is the highest, and the cell culture survival rate is high, making it suitable for slide preparation, staining, and fetal chromosome karyotype analysis. Chromosome genetic diseases can also be diagnosed, and gender determination can be made using amniotic fluid cell DNA for genetic disease diagnosis and metabolic disease other diagnostic tests. Measuring alpha-fetoprotein in the amniotic fluid can also help diagnose open neural tube defects in the fetus.