Nuchal Translucency Screening

{Pardon the tardiness on this topic -- I started this post months ago but never finished it.  Better late than never though, right?!}

The nuchal translucency scan takes place in the latter part of the first trimester, sometime during weeks 11-13.  It's a special ultrasound scan designed to screen for chromosomal defects -- particularly trisomy 13, 18 and 21 {Down Syndrome}, in addition to congenital heart defects.

Combined with specific blood tests, the nuchal translucency ultrasound is called the "first trimester screening".   It's a "non-invasive" way of assessing a baby's risk of chromosomal abnormalities, which means there are no needles and no physical risk to having the screening done.  Since this test is a screening {as opposed to a diagnostic test} it will not provide a 100% accurate or definitive answer -- it's more of a gauge of whether things look generally normal or problematic.  It gives the doctor a general indication of whether there is cause for concern, or need for additional testing, such as an amniocentesis or CVS test.

Here's an illustration of the measurement the ultrasound is designed to screen, along with a more detailed explanation of the screening taken from this source:

Source

The nuchal translucency is the fluid found at the back of your baby’s head and neck, just beneath the skin. The thickness of this fluid can be precisely measured and this is called the nuchal translucency (or NT) measurement. Normally the amount of fluid is small, producing a thin NT measurement.

We know that the amount of fluid can increase in the presence of certain conditions, producing a thicker NT measurement. Conditions associated with an increased NT measurement include some chromosome abnormalities (for example, trisomy 13, 18 and 21) and some structural problems (for example, heart abnormalities). An increased NT measurement does not always mean the baby has a problem but it does increase the risk.

{You can also read more about the NT test here and here.}

Our NT screening took place on November 7th, at 11.5 weeks gestation.  I have to admit, I was pretty nervous going into it, especially since we knew our first baby's miscarriage was a result of chromosomal abnormalities.  The 20 minutes or so spent in the office waiting room before being called in seemed to crawl by {especially since I had to pee but wasn't allowed}, and the several minutes during the screening during which the technician measured and took photos and notes but didn't provide any sort of medical insight lasted FOREVER.

The technician did, however, call our baby "cute" while she was conducting her measurements.  While I'm sure she says that to all the patients, we took it to heart and totally agree.  :)

After about 10-15 minutes of ultrasound measurements and photos, we were escorted in to meet with the doctor.  Thankfully, she had EXCELLENT news for us.  According to the screening, our chances of having a baby with any chromosomal abnormalities were extremely low.  Our specific risk profile for Down Syndrome is 1 in 4,463, and for Trisomy 18/13 is 1 in >10,000.  Better yet, the risk ratios matched that of a 20 year old mother, which made me feel pretty good since I'll be turning 33 in a couple weeks.  ;)  Needless to say, we both breathed a HUGE sigh of relief after receiving these results.  Though there are no guarantees, these odds are pretty favorable!

The NT is often followed up with a second trimester blood draw {usually called a multiple marker, triple or quad screen} to check on the probability of open neural tube defects.  We'll definitely be waiting for those results, but for now will just be thankful for these great numbers!