Patient's question:
I am 27 years old, 18 weeks pregnant, and had a Down syndrome screening. The alpha-fetoprotein result was 43.50 U/mL, with a MOM value of 0.85. The test was conducted on December 24, 2009.Doctor's answer:
Medical Analysis: Hello,1) What is Down syndrome screening?
1. Down syndrome screening is an indicator that can only be tested between weeks 15 and 21 of pregnancy. It is primarily used to determine the likelihood of the baby having Down syndrome. The results are for reference only and cannot be considered definitive. Additionally, whether this test is recommended depends on your medical condition, as determined by your doctor. The test involves a blood draw and is usually performed alongside other blood tests. The results are then combined with your recent ultrasound to assess the risk to the baby. If you are young and in good health, your doctor is unlikely to strongly recommend this test. However, if you have concerns, you can request it yourself.
Guidance:
2) This test screens for trisomy 21 (Down syndrome) in infants with congenital mental retardation. It involves a blood draw and is performed between weeks 14 and 19 of pregnancy. This screening is voluntary and based on informed choice. The risk of Down syndrome increases with the mother's age. The birth rate of Down syndrome children rises rapidly as the mother's age increases: at age 30, the rate is 3 per 1,000 births; for those over 35, it is 6 per 1,000 births; and after age 40, it exceeds 16 per 1,000 births. Therefore, it is generally recommended that women over 35 undergo amniotic fluid chromosome analysis. Since most women give birth before age 35, only about 20% of Down syndrome children are born to women over 35. Thus, screening is effective for reducing the birth of affected children in women under 35. However, screening is not definitive, and false positives and false negatives may occur. For high-risk pregnancies, amniocentesis with amniotic fluid chromosome analysis is necessary for final confirmation. Ultrasound plays a crucial role in prenatal screening for fetal abnormalities. It is widely used for screening and diagnosing severe limb abnormalities and other congenital defects. Ultrasound can also detect many fetal congenital anomalies and rare fetal malformations. High-resolution ultrasound images provide further anatomical information about the fetus. Therefore, ultrasound is one of the primary methods for screening congenital abnormalities. Additionally, ultrasound can adjust gestational age, identify multiple pregnancies, and detect stillbirths, significantly improving the accuracy of maternal serum biochemical screening. For this reason, it is highly recommended to have a 4D color Doppler ultrasound for fetal anomaly screening between weeks 22 and 26 of pregnancy.
3) Down syndrome is also known as trisomy 21, where the patient has an extra chromosome (instead of the usual pair) on chromosome 21. Down syndrome screening measures the levels of AFP and HCG in the mother's serum, along with her age, weight, and gestational age to calculate the risk value. The critical value is 1/275. A result above this indicates high risk, while a result below it indicates low risk. In the general population (under age 37), the probability of having a child with Down syndrome (DS) is 1 in 750. If the screening result is high-risk, amniocentesis is recommended. However, even if the result is high-risk, it does not necessarily mean the baby has Down syndrome. For safety, DS screening is still advised. DS screening is the abbreviation for prenatal screening for Down syndrome. Its purpose is to determine the risk of the fetus having Down syndrome through blood tests. If the screening result indicates a high risk of Down syndrome, further confirmatory tests—amniocentesis or chorionic villus sampling—should be performed.
……Lifestyle Advice:
DS screening can detect 60–70% of Down syndrome children. It is important to understand that DS screening only helps assess the likelihood of the fetus having Down syndrome but cannot confirm whether the fetus actually has the condition. For example, if the blood test results are elevated, it may indicate a higher chance of having a "DS baby," but it does not guarantee that the fetus has a problem. Similarly, older women (over 35) have a higher chance of having a "DS baby," but it does not necessarily mean their fetus has a problem. On the other hand, even if the test results are normal, it does not guarantee that the fetus is free of the condition. Pregnant women with abnormal DS screening results should undergo amniocentesis or chorionic villus sampling. If the results of these tests are normal, it can be 100% confirmed that the fetus does not have Down syndrome.