A nuchal translucency (NT) is an ultrasound measurement of the fluid at the back of a baby’s neck between 11 and 13+6 weeks of pregnancy. It is part of a screening test to determine if your baby is at an increased risk of certain chromosomal abnormalities. This is part of a prenatal screening test called Integrated Prenatal Screen (IPS). It includes the NT ultrasound and 2 blood tests. IPS is a screening tool to determine which babies are at increased risk for Trisomy 21 (Down Syndrome), Trisomy 18, and Open Neural Tube Defects (ONTD).
The NT ultrasound can also confirm the gestational age and provide some reassurance as to how your baby is developing. It is important to note that this ultrasound does not replace the recommended detailed ultrasound at 18-20 weeks because many organ systems are not fully developed at this early gestational period.
All babies have a fluid collection behind the neck, but babies with Down syndrome or trisomy 18 may have an unusually high amount. An increased nuchal translucency and an absent nasal bone in the first trimester are seen in 70% of babies with Down syndrome. Therefore, an NT ultrasound can provide valuable insight early in pregnancy. In addition, you will have blood work, called serum screening, that can be factored in with your nuchal translucency measurement to calculate your overall risk assessment. Adding an NT to blood tests reduces the chances of making an error called a “false positive,” where the tests indicate a positive screen when, in fact, everything is normal.
Who is eligible for NT ultrasound?
Within British Columbia’s public healthcare system, all women can have prenatal genetic screening to assess their risk of having a baby affected by Down syndrome, trisomy 18, and open neural tube defects. The province will fund NT ultrasounds for:
- women age 35 years and over at the time of their expected delivery
- women with a previous child/pregnancy with Down syndrome, trisomy 18 or trisomy 13
- women with a twin pregnancy
- women who are pregnant following IVF with ICSI
- women who are HIV positive
Who performs nuchal translucency ultrasound at The Kelowna Regional Fertility Centre?
NT’s are performed by a Fetal Medicine Foundation (FMF) certified ultrasonographer under the supervision of Dr. Wise, M.D., FRCS. Dr. Wise is an Obstetrician/Gynecologist who has successful completed the Nuchal Translucency Theory Course and Quality Assurance Program and oversees our FMF certified ultrasonographer.
On the day of your appointment, you will be asked to fill out a short history form about your medical and pregnancy history. You will have an ultrasound and an orientation session with one of our experienced nurses, who can review your ultrasound results, the prenatal screening options in detail, and give you an opportunity to ask questions. Please try to arrive with a comfortably full bladder in preparation for the nuchal translucency ultrasound.