Sequential Screen and MaterniT21®

Screening for High Risk Pregnancy Populations

2022-01-03Updated: 2022-04-28 Mansfield Miracles, Paul Daum, M.D.

NSL stands for Nuchal SonoLucency. This prenatal screening test (also called the nuchal fold scan) uses ultrasound to measure the clear ("translucent") space in the tissue at the back of your developing baby's neck, and is combined with measurement of two hormones in mom's blood.

That measurement can help assess your baby's risk for Down syndrome (DS) and other chromosomal abnormalities as well as major congenital heart problems. When combined with the Quad screen at 16 weeks you have the SEQUENTIAL SCREEN, which is the best of the noninvasive screens for down syndrome, trisomy 13, trisomy 18, and spina bifida.

Babies with abnormalities tend to accumulate more fluid at the back of their neck during the first trimester, causing this clear space to be larger. While the Nuchal SonoLucency screening test won't give you the definite diagnosis you'd get from more invasive tests like CVS and amniocentesis, it can help you decide whether you want to undergo MaterniT21® blood testing or amniocentesis. Only the amniocentesis or CVS placental sampling can be considered "diagnostic".

The Nuchal SonoLucency screening must be done when you're between 11 and 14 weeks pregnant. (The last day you can have it done is the day you turn 13 weeks and 6 days pregnant.)

The sonographer first confirms your baby's gestational age by measuring your baby from crown to rump to see if he's about the size he should be for his age. The sonographer positions the sensor, called the transducer, over your abdomen so that your baby's nuchal fold area shows up on the monitor, and measures the thickness of it on the screen with calipers.

Measurement of two pregnancy hormones is performed, and these three values are used to calculate your baby's risk of Down syndrome and trisomy 18. Trisomy 18 is like Down syndrome, but in most cases is a lethal condition.

NSL testing should be performed only by certified sonography specialists.  Call Mansfield Miracles at 817-477-0200 and schedule an appointment if you desire a screening evaluation.

If your initial results for trisomy come back higher than normal risk, there is a new test that measures free fetal DNA in the mothers blood. There are several names for the test but one of the most common is MaterniT21® Plus Screen also offered as "Harmony" maternal testing.

This screen will diagnose 99% of downs syndrome, 99.9% of trisomy18, and 91.7% of trisomy 13. This test is available through the hospital and is called "NIPT". This test is not recommended for low risk individuals, but can be offered to to all, with abnormal ultrasound findings, prior pregnancy with a baby with trisomy, positive screening test for chromosomal trisomy (sequential, quadscreen, or integrated screen.)

All of these services can be offered through our office at Mansfield Miracles located in the professional building of the Methodist Mansfield Medical Center.