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Maternal Serum Screening

Down Syndrome, Trisomy 18 and Neural Tube Defects



First Trimester Serum Screening

Slide 6

March 2011

Moving on to each type of screening, first trimester screening is performed between 10 and 14 weeks of gestation. It provides a risk for Down syndrome and trisomy 18.

The markers used on the risk calculation are 2 serum markers: Pregnancy-associated plasma protein A (PAPP-A) and human chorionic gonadotropin or hCG. Decreased levels of PAPP-A before the 14th week of gestation are associated with an increased risk for Down syndrome and trisomy 18. Whereas increased levels of hCG are associated with an increased risk of Down syndrome. The third marker is the fetal nuchal translucency which is performed by ultrasound.

First Trimester Serum Screening

 


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