First Trimester Screening
Our perinatology service offers first trimester screening. This non-invasive screening is a combination of an ultrasound of the baby and a blood test on the mother. The ultrasound examines the thickness of skin along the baby’s head, neck, and back called the “nuchal translucency”. If it measures within the normal range, aneuploidy such as Trisomy 21 (Down Syndrome), Trisomy 18 (Edwards Syndrome) or Trisomy 13 (Patau Syndrome) is much less likely. If it measures thicker than expected, there is a greater association with a chromosomal abnormality. A normal nuchal translucency measurement excludes up to 70% of Down’s infants. The other portion of the first trimester screen involves a blood test for HCG and pregnancy-associated plasma protein A (PAPP-A).
Each first trimester factor (nuchal translucency, blood studies, and statistical tables) provides valuable information and together, the results give us a more complete picture of the risk of aneuploidy. If normal, this combination of tests excludes up to 85% of Down’s infants.