Prenatal Screening for Fetal Aneuploidy
It is a routine practice to offer first or second trimester serum screening test to identify fetuses at
increased risk of open neural tube defects and chromosomal abnormalities.
Calculation of risk for Down syndrome,...
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Prenatal Screening for Fetal Aneuploidy
It is a routine practice to offer first or second trimester serum screening test to identify fetuses at
increased risk of open neural tube defects and chromosomal abnormalities.
Calculation of risk for Down syndrome, trisomy 18 and open neural tube defects (ONTDs) is done by
combination of variables which include biochemical serum markers, maternal age, ethnicity, weight,
diabetic status, smoking habit and if available, nuchal translucency (NT). Depending on the results of
the screening tests, diagnostic tests (amniocentesis, CVS) are offered.
First trimester screening includes pregnancy-associated plasma protein A (PAPP-A) and free human
chorionic gonadotropin. Second trimester quad marker include alpha-fetoprotein (AFP), unconjugated
estriol (uE3), human chorionic gonadotropin (hCG) and inhibin-A. The first blood test is collected
between 10 – 13 weeks and the second between 15 – 20 weeks. Test results are available within 7
days.
After pre tes
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