Women & Infants' Prenatal Diagnosis Center, in collaboration with our Division of Prenatal and Special Testing, offers additional prenatal screenings for Down syndrome: two nuchal translucency (NT) based screening tests. The First Trimester Test and the Integrated Test combine the first and second trimester tests into a single screening result.
Nuchal translucency is an ultrasound measurement of a fluid-filled space measuring approximately one millimeter at the base of the neck of a developing fetus. This measurement detects 85 to 90% of all cases of Down syndrome, when coupled with a blood test at 10 to 14 weeks, and taking into consideration the mother’s age.
The full Integrated Test has the highest screening performance of any test yet developed. The expected detection rate for Down syndrome is 85 to 90%, with a screen positive rate of only one to two percent.
Patients who desire even earlier prenatal diagnosis and who understand that follow-up diagnostic procedures may still be needed, may choose the First Trimester Test, which combines three markers: NT and serum PAPP-A and hCG. With an expected detection rate of 85% and a false positive rate of five percent, those women who are screen positive may need to undergo chorionic villus sampling (CVS) no later than the 12th week of gestation.
The accuracy of these tests may also allow the patient to minimize the number of invasive procedures – such as CVS and amniocentesis – that do carry risk to a developing fetus.
For more information about NT measurement and prenatal screening, women should speak with their health care provider or call the Prenatal Diagnosis Center at 401- 453-7510.