Traditional screening tests measure protein and hormone levels in your blood and estimate the chance that the developing baby has a chromosome condition.
Because it is a blood test, there is no risk to your pregnancy.
The blood test is often combined with an ultrasound measurement, called the nuchal translucency (NT), to improve result accuracy. This type of testing is generally restricted to certain periods of time during the pregnancy.1
The detection rate is the chance that the test will correctly identify a pregnancy that has one of these conditions. Detection rates with traditional screening may range from 69-96% for trisomy 21, depending on the method used.1
Sometimes a test can indicate a high chance for a chromosome condition when the developing baby does not have it. This is called a false positive result. With traditional screening, about 1 in 20 women might receive a false positive result.1
- ACOG Practice Bulletin No. 77, January 2007. Obstet Gynecol; 109(1):217-27.
No screening test is designed to detect all possible conditions. Screening tests help identify pregnancies with an increased chance of certain chromosome conditions. With screening tests, false positive and false negative results will occur.
Women who have an increased chance on their screening test should consult a healthcare professional who can recommend additional invasive confirmatory or other testing.