1st Trimester risk assessment testing is a combination of an ultrasound exam and a blood test to measure two chemicals normally present in the blood of all pregnant women.
The ultrasound measurements used in the screen are the nuchal translucency (NT) which is the thickness of a fluid filled space at the back of the baby’s neck and the crown-rump length (CRL). The blood test measures free beta human chorionic gonadotropin (free Beta hCG) and pregnancy associated plasma protein-A (PAPP A). These proteins are made by the baby or the placenta. The NT measurement and levels of free Beta hCG and PAPP A are used to calculate the specific risk for your baby to have Down syndrome or Trisomy 13 or 18.