Patient's question:
Medical Description: Hello, I had prenatal screening on August 2nd, and the results are as follows:Trisomy 21: 1/946 (Low risk)
Trisomy 18: 1/334 (High risk)
Trisomy 13: 1/11,388 (Low risk)
Open neural tube defect: Low risk
However, my actual age is 24, but the report says I am 25. My actual gestational age is 108 days, 15 weeks + 3 (I had an ultrasound report before, but the doctor didn’t even look at it and used his own calculated date instead). The report incorrectly states 118 days, 16 weeks + 6.
Will this affect the prenatal screening results? I showed the report to a doctor, and he said it would, but he didn’t explain further and just told me to have an amniocentesis. Should I have an amniocentesis, or should I go to another hospital?
Doctor's answer:
Hello. Generally, the Down syndrome screening is done between 14 and 20 weeks of pregnancy. It screens for trisomy 21, trisomy 18, and congenital genetic metabolic diseases. If the test indicates a high risk, further testing is required. Of course, a high risk does not necessarily mean the person definitely has the disease; it simply means the possibility is higher. There are three types of further tests: one is ultrasound, one is prenatal non-invasive DNA testing, and one is amniocentesis. Naturally, the accuracy of these three methods increases progressively, and so does the risk level. Therefore, prenatal non-invasive DNA testing is more commonly performed now. The optimal time for amniocentesis to extract amniotic fluid for prenatal diagnosis is between 16 and 20 weeks of pregnancy. This is because the fetus is smaller at this stage, and there is relatively more amniotic fluid. The fetus floats in the amniotic fluid, surrounded by a wider band of amniotic fluid. When using a needle to puncture and extract amniotic fluid, it is less likely to injure the fetus.