Toward the end of your first trimester, your practitioner may recommend i of several prenatal screenings, including nuchal translucency.

These screening tests are recommended for all pregnant women and help make up one's mind the odds that a babe has a chromosomal disorder or congenital middle defect, although they can't diagnose these conditions.

Here's when and why nuchal translucency is recommended and what you tin can look from this common screening.

What is a nuchal translucency examination and what does it mensurate?

nuchal medical illustration

A nuchal translucency screening, or NT screening, is a specialized routine ultrasound performed at the stop of the offset trimester of pregnancy. Information technology helps doctors make up one's mind if a baby is statistically more probable to accept a chromosomal abnormality.

NT focuses on a small, clear infinite at the back of a growing baby's neck called the nuchal fold. Experts have establish that this spot tends to accumulate fluid in babies with chromosomal abnormalities.

Babies with increased fluid at the base of their necks are at a statistically increased adventure of having a chromosomal problem, such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18) or Patau syndrome (trisomy 13).

All of these conditions involve having an actress copy of chromosomes on a specific set of chromosomes (chromosome 21, xviii, or 13, respectively). They can crusade intellectual disabilities and mild to severe birth defects. The odds of a baby having a disorder increase with a female parent'southward historic period, simply they can happen to anyone at whatsoever age.

Keep in mind that nuchal translucency is not 100 percentage accurate. It'due south a prenatal screening, which ways it can't diagnose whatever condition.

Because false positives with the NT screening lone are relatively mutual, it's often combined with a claret test to offer more insight into the relative odds of your babe existence built-in with a genetic disorder.

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What is a normal NT measurement?

Normal NT measurements vary depending on how far along you are in your pregnancy.

In full general, most doctors consider a normal screening NT measurement at 12 weeks to be under 3 mm.

Who should go a nuchal translucency screening?

A nuchal translucency screen is recommended for all significant women and is often one of several routine prenatal tests during the showtime trimester.

It's ultimately upward to you whether you have prenatal testing. The results can help you lot make prenatal care decisions. If follow-upwardly testing diagnoses a chromosomal disorder, it can allow you to prepare in advance for your child's special needs.

Although NT is widely available, some rural and urban areas may not have the resources to perform the procedure.

When a nuchal translucency screening is done

NT screening is usually done betwixt weeks 11 one/2 and 13 1/2, but it must exist performed between calendar week 10 and week 13 of pregnancy. Subsequently that, the tissue gets thicker and is no longer translucent, so exam results become inconclusive.

How an NT screening is done

An NT is a special type of ultrasound using a very sensitive but safe machine. A sonographer will apply a transducer (wand) to the outside of your stomach to measure out your baby from crown to rump and check that the fetal age is accurate. Then he or she volition locate the nuchal fold and measure out its thickness on the screen.

Those measurements, plus your age and infant's gestational age, volition be entered into an equation that calculates the probability of a chromosomal abnormality. Although this number can't give you a definitive diagnosis, it can help you decide whether you want to undergo diagnostic testing.

Nuchal translucency and the first trimester combined screening

Nuchal translucency screening has a relatively high rate of error when performed by itself. To improve the accuracy of results, your practitioner will likely offer what's known equally a combined screening.

In a combined screening, NT ultrasound results are paired with one or two claret tests that measure and compare your levels of hCG and PAPP-A (pregnancy associated plasma protein A). These two hormones are produced by the fetus and passed into the mom's bloodstream.

How accurate is nuchal translucency?

NT results by themselves have an accuracy rate of most 70 percent. That means that the test misses 30 percent of babies with Down syndrome or other chromosome disorders. Including the NT every bit part of a first trimester combined screening improves detection to between 83 and 92 pct.

Pairing the results of the nuchal translucency with other screening tests in the first trimester further improves the accurateness. The integrated screen, which combines the NT screening, measurements of the hormone PAPP-A, and the quad screen, improves Downwardly syndrome detection rates to between 94 and 96 percentage.

The results of an NT screen tin also be combined with noninvasive prenatal testing (NIPT). NIPT is the most accurate of all prenatal screenings; by itself, it'south 99 percent accurate at detecting Down syndrome.

What if your NT results are aberrant?

If your nuchal translucency screening or any other prenatal screening results indicate that your baby may exist at an increased risk of having a genetic abnormality, your practitioner will probable suggest a diagnostic examination like chorionic villus sampling (CVS) or amniocentesis.

He or she may also suggest talking to a genetic advisor, who can better explain what the results mean.

Since aberrant NT measurements are also associated with fetal heart defects, your practitioner might recommend a fetal echocardiogram at around 20 weeks to look at your babe's heart. An abnormally thick nuchal measurement should be taken into account at the 20-week beefcake scan and special attending paid to scanning the eye.

Increased NT measurements may too be linked to a very slightly higher risk of preterm birth, then you may be monitored for that besides.

Keep in mind that all pregnancy screenings, including the nuchal translucency and the associated bloodwork, don't directly test for chromosomal problems. That means they tin't diagnose any specific condition.

An aberrant consequence on the nuchal translucency or combined screening test doesn't mean that your babe has a chromosomal abnormality. They just mean that there's a statistical likelihood of having a trouble. That's why your doctor will suggest follow-up diagnostic testing.

Try not to overthink your results. Many women who accept an abnormal effect on their screening test go on to have a perfectly normal, healthy child.

Also continue in mind that a normal result on a screening exam is not a guarantee that your baby does not take a chromosomal defect, although it does mean that it's very unlikely.

How to ready for a nuchal translucency screening

Experts say you'll get the all-time nuchal translucency results if you undergo the ultrasound with a full bladder, and so effort not to get to the bath right before y'all have your exam. The person performing the NT scan may also enquire you to drink a glass of h2o before you begin.

Nuchal translucency risks

Both the ultrasound and the accompanying blood tests are painless (unless you count the needle prick for the claret examination) and carry no risk to you or your baby.

Faux positives are relatively mutual with the NT screen alone, which may lead to follow-up procedures that nowadays greater risk and unnecessary worry. But try to go along it in perspective: The odds of having a completely healthy baby are overwhelmingly in your favor.