Can Early Pregnancy Tests Detect Edwards Syndrome and NTDs?

Can Edward's syndrome be detected in early pregnancy?

Dear Doctor: The second trimester quadruple marker test can simultaneously detect neural tube defects and abnormalities of the 18th chromosome (i.e., Edwards syndrome).
Does the first trimester screening (nuchal translucency + blood test) include these two items as well? Thank you for your response.

GIGI, 20~29 year old female. Ask Date: 2012/09/17

Dr. Liu Yuhong reply Obstetrics and Gynecology

"Does the first trimester screening (nuchal translucency + blood test) include the two items mentioned above?" The first trimester screening (nuchal translucency + blood test) can also screen for neural tube defects and abnormalities of the 18th chromosome pair, but it is important to understand that screening does not equate to confirmation.
Confirmation of fetal neural tube defects requires ultrasound, while confirmation of abnormalities in the 18th chromosome pair necessitates amniocentesis for chromosomal analysis.
Similarly, the diagnosis of Down syndrome also relies on amniocentesis for chromosomal analysis.
Both first trimester and second trimester screening tests are tools for screening, not for confirmation.

Reply Date: 2012/09/17

More Info

In early pregnancy, screening tests play a crucial role in identifying potential risks for certain congenital conditions, including neural tube defects (NTDs) and chromosomal abnormalities such as Edwards syndrome (trisomy 18). The initial screening, often referred to as the first-trimester screening (or "初唐" in Mandarin), typically involves a combination of ultrasound measurements (such as nuchal translucency) and maternal blood tests.

To address your question directly: the first-trimester screening (which includes nuchal translucency measurement and blood tests) can indicate the risk of both neural tube defects and chromosomal abnormalities, including Edwards syndrome. However, it is important to understand that this screening is not definitive. It is designed to assess risk rather than provide a conclusive diagnosis.

Neural Tube Defects (NTDs) and Edwards Syndrome Screening
1. Neural Tube Defects (NTDs):
- NTDs, such as spina bifida and anencephaly, occur when the neural tube does not close properly during early fetal development. The first-trimester screening can help identify an increased risk for NTDs, but it is not a diagnostic tool. The most common marker used in the first-trimester screening is the measurement of maternal serum alpha-fetoprotein (AFP), which is more commonly assessed in the second trimester.

- If the first-trimester screening indicates a higher risk for NTDs, further diagnostic testing, such as a detailed ultrasound or amniocentesis, may be recommended for confirmation.

2. Edwards Syndrome (Trisomy 18):
- Edwards syndrome is a serious genetic condition caused by the presence of an extra chromosome 18. The first-trimester screening can assess the risk of this condition through a combination of nuchal translucency measurement and specific blood markers (such as pregnancy-associated plasma protein A (PAPP-A) and free beta-human chorionic gonadotropin (β-hCG)).

- If the screening suggests a high risk for Edwards syndrome, diagnostic tests such as chorionic villus sampling (CVS) or amniocentesis are typically recommended to confirm the diagnosis.

Importance of Follow-Up Testing
While the first-trimester screening can provide valuable information regarding the risk of NTDs and Edwards syndrome, it is essential to follow up with more definitive testing if the initial results indicate a higher risk. These follow-up tests, such as ultrasound or invasive procedures like amniocentesis, can provide a clearer picture of the fetus's health and genetic status.

Conclusion
In summary, the first-trimester screening can indicate the risk of both neural tube defects and Edwards syndrome, but it does not confirm these conditions. If you have concerns about your screening results or the health of your pregnancy, it is crucial to discuss them with your healthcare provider. They can provide guidance on the next steps, including any additional testing that may be necessary to ensure the best possible outcomes for you and your baby. Regular prenatal care and open communication with your healthcare team are key components in managing your pregnancy health effectively.

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