First Trimester Down Syndrome Screening Tests

First trimester screening (also referred to as BUN test) is designed for women interested in determining whether their baby is at an increased risk for Down syndrome and Trisomy 18.  These are both chromosomal abnormalities that result from the presence of an extra chromosome in every cell of the body. 

These abnormalities can occur sporadically (with no family history) to women of all ages, but they are more likely to occur in women over 35 years old. 

Until recently, non-invasive screening techniques that were used to determine the risk of Down syndrome in a pregnancy could not be performed until the second trimester.  Now, a first trimester screening can determine your risk of Down syndrome and Trisomy 18 much earlier in your pregnancy, with up to a 90% detection rate.

Midwest Center for Women’s Healthcare offers first trimester Down syndrome screening tests, which are typically performed between 11 and 14 weeks gestation.  The screening consists of a combination of an ultrasound exam and blood test:

• The ultrasound demonstrates a fetal heartbeat and determines gestational age.  Then, the amount of fluid accumulation behind the neck of the baby, called nuchal translucency (NT), is measured. 
• A blood specimen is analyzed for two chemicals called Beta human chorionic gonadotropin (free Beta), and pregnancy associated plasma protein-A (PAPP-A) which are normally found in the blood of all pregnant women. 
• The results of the ultrasound exam will be combined with the results of the blood test to estimate a specific risk, high or low, for Down syndrome and Trisomies 18 and 13.  

Several of our locations provide first trimester Down screening tests.  Please ask your physician or Certified Nurse-Midwife whether this test is appropriate for you and your baby.