What should I do if the Down syndrome screening indicates a high risk for trisomy 21?
Aug 20, 2021
Source: Cainiu Health
Dr. Zhang Chunxia
Introduction
What to Do If the Down Syndrome Screening Indicates a High Risk for Trisomy 21:
Down syndrome screening yields a risk probability—not a definitive diagnosis—calculated based on maternal serum markers, laboratory test results, gestational age, maternal weight, and other factors. A “high-risk” result does not equate to a confirmed diagnosis. Specifically, a calculated risk greater than 1 in 270 is classified as high-risk, indicating an elevated likelihood that the fetus has Down syndrome.
The results of Down syndrome screening reflect a probability—not a definitive diagnosis. They estimate the fetus’s risk of having Down syndrome based on maternal serum markers, laboratory test results, gestational age, maternal weight, and other factors. A “high-risk” result does not equate to a confirmed diagnosis.A screening result indicating a risk greater than 1 in 270 is classified as high-risk, suggesting an elevated likelihood that the fetus has Down syndrome.
When Down syndrome screening yields a high-risk result, further diagnostic options include non-invasive prenatal testing (NIPT) and amniocentesis. NIPT involves drawing a peripheral blood sample from the mother to isolate cell-free fetal DNA circulating in her bloodstream; it specifically analyzes chromosomes 21, 18, and 13 to detect numerical abnormalities.
Amniocentesis is a prenatal diagnostic procedure in which amniotic fluid is extracted and fetal cells cultured to perform chromosomal analysis. It provides a more accurate and definitive diagnosis, whereas NIPT remains a highly sensitive screening tool—not a diagnostic test.
