NT Scan

With Littles -- November 2006
Early in my pregnancy with Littles, my OB told me about what was then a relatively new test, known as the nuchal translucency (NT) scan. The non-invasive scan could detect Down syndrome (trisomy 21), as well as two lesser-known and more serious chromosomal disorders, trisomy 13 and trisomy 18. It was covered by insurance and it included an ultrasound :) So we decided to do it.

The NT scan requires high-powered ultrasound equipment that most OB offices don't have in-house. So on the appointed day, we went to the hospital where Littles would eventually be born. We first met with a genetic counselor, who went over a family history and explained the test in detail to us. Later that day, we had the ultrasound, and I also gave some blood for further testing. We got the results back within a week or so, which indicated that Littles was at low risk.

At the time, the NT scan was considered optional for women like me, who had no risk factors for chromosomal disorders. (Risk factors include advanced maternal age or a family history of chromosomal disorders.) A few months later, ACOG started recommending NT scans for all pregnant women, regardless of risk level. That recommendation still stands today.

In the years since, I've talked to lots of other women about the NT scan, and have been surprised to hear that many of them skipped it, mostly based on misinformation. Some of the typical reasons I hear for not getting the NT scan:

• "It gives a lot of false positives, and I don't want to worry for nothing." One of the things the genetic counselor explained to us was that you cannot get a "false positive" on an NT scan, because it is not designed to conclusively state whether or not the baby has a chromosomal disorder. It simply states whether the baby is at "high risk" for one. To give an example, one of my friends' babies was deemed high risk and given 1 in 200 odds of having Downs. He was later born perfectly healthy. But this was not a "false positive." 1 in 200 odds meant that he had a 99.5% chance of being born healthy, and indeed, he was!
  
  Even the high risk designation is relatively uncommon. It's given to about 5% of babies. Hardly "a lot."
  
• "I'd never abort a baby with Downs, so why bother testing? It wouldn't change anything for me." I wouldn't abort a baby with Downs, either, but I'd sure want to be prepared! This has become increasingly important for me in my subsequent pregnancies, because not only would I want some extra time to prepare myself for a child with special needs, but I'd also want some extra time to prepare the older kids.
  
  Also, the NT scan doesn't just test for Downs. It also tests for trisomies 13 and 18, which are often fatal in utero or result in a short (<1 year) and very painful life. I might consider aborting for those, and if I didn't abort, I would definitely want some time to prepare emotionally for carrying a baby who might not stick around very long, if at all.

I've also heard many more stories that have convinced me of the importance of getting an NT scan:

• The anatomy scan (an ultrasound usually performed at around 18-20 weeks) looks for signs of the same disorders that the NT scan identifies. These are called "soft markers" because they are usually present in babies with chromosomal disorders, but many healthy babies have them as well. If I have a clean NT scan and then have soft markers identified at the anatomy scan, I can take comfort in the knowledge that the NT scan rarely comes back as low risk for a baby who truly does have a chromosomal disorder, so the soft markers are almost certainly "soft" in my case. If I don't have an NT scan and then have soft markers identified at the anatomy scan, I have no such reassurance.
• Since the NT scan includes an ultrasound on high-tech equipment, it affords the opportunity to identify other problems with the baby (besides chromosomal disorders) very early on. One woman's baby was diagnosed with spina bifida at her NT scan. They were able to operate on the baby in utero at 17 weeks. The problem likely would have been picked up at her anatomy scan, too, but that would have been later in the pregnancy and the operation might not have been as successful.
• Tragically, another woman skipped the NT scan and then was diagnosed with amniotic band syndrome at her anatomy scan. By that time, the condition was so far advanced that it was fatal. Had she had an NT scan, the condition could have been diagnosed early enough to take steps to address it, quite possibly saving the baby.

With Noob -- July 2009
Because I knew all of this, I was a little surprised when my midwives didn't talk about the NT scan early on in my pregnancy with Noob. So I asked about it at a regular appointment at 10 weeks. F seemed a little taken aback, but had no problem giving me a referral to a nearby perinatologist to get the screening done.

He did a great job with the ultrasound, taking his time to not only get a good nuchal fold measurement (the entire goal of the ultrasound -- the thicker the nuchal fold, the higher the risk of chromosomal disorders) but also to take a peek at the rest of Noob's body and give me some good pictures to show my husband, who couldn't make it to the ultrasound.

And once again, when the bloodwork results were final, I got the reassurance of being deemed low risk.

With Q -- December 2011
Since I was planning homebirth, I was particularly keen on getting the NT scan done. If there are any medical concerns that might affect our homebirth plans, I'd want to know that as soon as possible.

I assumed, correctly, that most of C's patients weren't interested in getting an NT scan. As a result, she had no existing relationship with a perinatologist or other facility capable of performing it. So I went back to Dr. C for a referral. Of course, she doesn't do these types of referrals often, either, so this ended up requiring quite a bit of back-and-forth, further delayed by the fact that this was right around the holidays and so there were some office closures in there as well. Since the NT scan must be done by 14 weeks, it came right down to the last minute, but I finally managed to get the referral and get in for an appointment on the next-to-last possible day.

I was thoroughly unimpressed by the perinatologist who did the scan. It was the shortest of the three NT scans that I've had. The perinatologist quickly measured the nuchal fold and told me that the measurement looked good. Then he said, "Do you want to know the sex of the baby?" as I could see him moving down Q's body towards his/her bottom. "No! I don't!" I told him quickly. We don't plan to find out the sex. "Well, then look away," he said. I closed my eyes and he poked around for a minute or so and then told me that the scan was complete.

When I relayed this story to C at my next appointment, she explained that many perinatologists are trying to get good at early guesses as to the baby's sex. When I was pregnant with Littles, most ultrasound techs were reluctant to take a guess as to the sex at 16 weeks, nevermind in the first trimester. Now, a lot of women do walk out of their NT scans with a guess. Which is insane to me, because at 12 or 13 weeks, male and female genitalia look almost identical. But anyway, C thought that the perinatologist was using Q to practice his skills at distinguishing between the two sexes that early on.

It all happened really fast, but after the fact, I was rather peeved. I feel that the perinatologist should have explained why he wanted to look -- whether it was for medical reasons or for his own "practice" -- and granted me the opportunity to give or refuse consent. Normally, looking at a child's genitals for no good reason without the parent's consent is not just rude but is grounds for persecution. Why should it be any different on an ultrasound?