What does nuchal translucency mean to me?
(**SCROLL DOWN TO THE WORD *NEW* TO SEE THE LATEST POSTINGS OF MEDICAL STUDIES ON NUCHAL TRANSLUCENCY**)
A measurement is taken of the fluid behind the baby's neck at about 10-12 weeks gestation. In Ultrascreen, it is combined with a blood test from the mother to determine the risk of genetic defect or heart problem. (The blood test measures hormones called PAPP-A and free beta HCG. A PAPP-A measurement that is very low and HCG that is very high can indicate a higher risk of a problem.)
In the vast majority of cases, the baby is healthy. So why the thick fluid behind the neck? Scientists posit that the fluid collects when the heart can't circulate it fast enough, which is to be expected in tiny fetuses just beginning to develop.
This study shows that scientists are trying to figure out why women get positive Ultrascreen results (signifying their baby is at risk) when the baby is actually healthy.
Here's a great page that explains many terms and shows some charts of risk factors and blood test levels.
Here's my story:
I went for a routine ultrasound at about 9 weeks to "date the pregnancy." I knew what my dates were, but they were offering, and insurance covered it. I figured, hey, free peek at the baby! It was not done in my doc's office, and the ultrasound tech looked really young. She told us she was concerned by the measurement of the fluid behind the neck. It measured 3.6mm. She sent us for ultrascreen. Meanwhile I googled the topic and was certain my baby would have Down Syndrome or Trisomy 13 or something. At the Ultrascreen, the tech said she didn't see anything that looked like a bad sign. My blood work was fantastic, in the lowest of the risks. (free-hcg - .43 [this is pretty low. High is supposed to be a Trisomy indicator.] PAPP-A - 60th percentile. [Normal]) But they sent the 3.6mm measurement along with the bloodwork to the company that crunches the numbers in their software. I know the tech did not measure that in any of her three measurements, but they are supposed to send the largest one. My risk factor was elevated because of the measurement, which I have since learned is extremely difficult and can be subjective.
I continued to worry, but did not want any invasive tests.
I did agree to the Level II ultrasound and the fetal echocardiogram, which is an ultrasound of the baby's heart. Both found nothing to worry about.
Michael is now eight months old and shows no signs of any problems.
I wish I had never done this test, as it ruined my peaceful feelings about the pregnancy.
The most popular place people have to discuss getting a positive screen result for nuchal translucency (that is, the measurement of the fluid behind the baby's neck that is higher than 3.0mm/3.0 millimeters) is the comments section of babycenter.com
Here is the link:
Many of the posters there are scared and just learning about Ultrascreen and NT. While the Ultrascreen (nuchal translucency measurement plus blood test of the mother for certain markers and hormone levels) is sold as being better than the AFP, this is because it is done earlier in pregnancy. It actually has about the same false positive rate. It does help eliminate some mothers who would have automatically been told to do an amniocentesis in the past. (Those 40 and older, for example.) But it also scares the heck out of young mothers who have to deal with the fear that something could be wrong for almost seven whole months until their baby is born.
I will post more links as I find them.
LIMITATIONS OF USING NT TO PREDICT PROBLEMS:
This study points out a fairly big difference in an NT of 2.5mm versus 3.5mm.
This is a nice even-handed scientific explanation that points out only 10% to 15% of babies with increased NT actually have a genetic problem. It states that high NT also indicates a 15% risk of a heart problem. That does not mean 30% of babies with high NT either have a genetic problem or a heart problem. There is some overlap between those two groups. Many babies with a genetic/chromosomal problem, especially Down's Syndrome, also have heart problems. So more than 70% of babies with high NT are healthy and typical at birth and on into childhood.
1) This one shows the NT changes depending on the heartbeat.
2) This study concludes high NT measurements in babies with trisomy may be caused by heart failure. (For those that don't know, heart failure doesn't mean the heart stops. The medical definition is a chronic condition where the heart can't keep up. The symptoms in otherwise healthy adults are shortness of breath and fatigue.)
NT AND CORD AROUND NECK:
This study says when the cord is around the neck (called nuchal cord) this can cause an increased NT in a baby who has no problems and will be born normally. So if the cord is seen around the neck, coupled with high NT, this should be reassuring to the patient, because the "nuchal cord" is a likely cause of high NT.
NT AND WHAT DOCTORS STILL DON'T UNDERSTAND: This study states upfront: The ultrasonographic measurement of nuchal translucency thickness at 10-13 weeks of gestation is accepted as an efficient method of screening for chromosomal abnormalities. However, the underlying mechanism producing increased nuchal translucency thickness is still poorly understood. In the study of 65 fetuses, 17 had high NT measurement. Five of those turned out to have chromosomal abnormalities.
NASAL BONE: This study shows the absence of the nasal bone is an independent factor that should be considered, and can't be predicted simply using the PAPP-A and free HCG blood test.
This abstract from a 2003 study shows that looking for the nasal bone has a lower false positive rate than using NT.
DWARFISM: This study follows one expectant mother who had a normal CVS test after a high NT. A later ultrasound found skeletal evidence of dwarfism. A DNA test was done confirming this.
OUTCOMES FOR HIGH NT CHILDREN:
This study's abstract states that if there is increased NT but the CVS or amnio is clear and the 20-22 week ultrasound is normal, "the risk of an adverse perinatal outcome and postnatal developmental delay is not statistically increased" over those with a normal NT!
This study (FULL TEXT PDF!) published in 2007 followed children who had increased NT (greater than 3.5mm) but looked normal on their ultrasounds. The study found those children were not at greater risk for developmental delays at age 2. "Counseling should emphasize that when the karyotype is normal and no fetal structural malformation was missed prenatally after resolution of nuchal thickening, the prognosis is not impaired at the age of 2 years."
ANXIETY AND PREGNANCY
At least all your worrying isn't hurting the baby, according to this study released this month. (Abstract)
NT AND MATERNAL AGE
This study abstract shows the Ultrascreen (NT, blood tests, etc) is much more accurate than using maternal age alone. However the mother's age is usually factored into the formula at most labs. They take the NT measurement, the blood test results and maternal age and put them in a computer formula to give you your new risk result. This is the ratio you receive as your screening "result." It is just a risk factor, not a diagnosis. Doctors usually compare this risk factor to the general risk calculated by maternal age alone. If your risk is greater than normal for your age, usually you will be referred for follow up testing. If your risk factor is lower than normal for your age, you will usually be told everything is likely to be OK because the test shows you have a decreased risk for problems compared to other mothers your age.
NT instant results
In some practices, women are being given the Ultrascreen dried blood sample card at home to mail in prior to the test. After the ultrasound, instant results are given. Instant results have correlated with an increase in CVS rates. (Probably because more people know they want to have CVS before it is too late for the test.) See abstract here.
What fetal echocardiogram and Level II ultrasounds are like:
Here's a post of mine to babycenter from 2006, describing additional prenatal testing I had as a result of a high risk factor from my ultrascreen:
Regarding fetal echo - The perinatologist said 22 weeks was better than 20, because the heart is more developed, but they were only able to schedule me in at 20.5 weeks, so that's when I had it done. It was 2 days after my Level II u/s, so I can compare it for you. At the Level II, she spent probably 10-15 minutes looking at the heart and checking for the 4 chambers. At the fetal echo, she spent 30 minutes just on the heart and the umbilical cord. She would get a really good image, then record the heart beating for about 10 to 15 seconds. She would add in this red and blue color that somehow showed how the blood flows. She turned me on each side for different views, also. She also did the same for the umbilical cord with the colored blood flow thing. At the end, a cardiologist came in to talk to me. She said she could see all the valves (I don't understand how she could see them, but I trust her.) She said all the blood was flowing the right way, and she saw no large holes in the heart. (The smaller ones they can't see, but would also be less likely to be a serious problem at birth.)
Level I vs. Level II u.s: I had a Level I with my daughter, and it was mostly visualizing the 4-chambered heart, making sure the cord has 3 vessels, and measuring the head and long bones. Lots of measuring.
With the Level II, she was specially trained to look for markers of a genetic anomaly. She looked for the nasal bone, and 3 bones in the pinky finger. She carefully measured the legs, which can be short in DS babies. She looked for all the parts of the brain. She looked for calcium deposits in the heart or the bowel and for fluid collecting anywhere. In general it was more thorough and the images seemed more clear, and she was looking for the markers.
New Amazon Standard
Here are some excerpts from posts I wrote to Babycenter forums in 2006.
I just try to keep in mind that babies don't come with guarantees. Even someone whose baby is perfect at birth can develop autism or leukemia or something awful. The only difference in diagnosing during pregnancy is that you can worry about something you don't even know whether it's real or how bad it will be. My friend whose daughter has Down Syndrome said if they had known ahead of time, their worry would have been way out of proportion to reality, because it is just really not that bad. But I know there are other syndromes and such that can be fatal and moms would want to know. It's just such a tough situation not really knowing, but try to keep in mind that none of us ever know. Even after they are born, anything can happen, so we never get to stop worrying. It's just a different and worse kind of worry we have all gone through with these scary tests. My best to everyone!
Reading this board and looking at studies I just came to my own conclusion that I really didn't think in my heart that anything was wrong with the baby. I just decided after doing research that increased nuchal fluid was not a strong enough indicator. Sure, I was worried sick for a couple weeks, my heart racing, which I knew wasn't good for the baby. But since I never had the NT test with my daughter, I figured hers could have looked exactly the same and we would never have known. I concentrated on being angry because I felt a little tricked into doing a test that has such a high false positive rate. I wrote a long letter to my doctor explaining why I didn't want additional testing. Thinking along those lines really cemented the idea in my mind that I really didn't think anything was wrong, and if it was, there is nothing I could do about it anyway.
More on worrying
Another babycenter post.
In the beginning, I really thought this was a bad sign and surely something was wrong, but the more I looked into it and read stories on this board of the many, many healthy outcomes, I just felt at peace and truly believed in my heart the baby is healthy. I guess I just ran out of steam worrying - I couldn't sustain that kind of worry, being pregnant and having a 1-year-old. Physically, I couldn't take it, so I had to come to some peace. It also helped talking to my friend, who told me how great his daughter (who has DS) is. I don't know how other people cope. Once I came to that peace, any remaining anxiety I had was channeled into anger over how unreliable these tests are, and how it feels like everyone is trying to make money off me, and how hard they make it to refuse tests. My doc believes the tests don't cause extra worry, because you will be worried about the baby's health anyway, and you will be relieved when the tests are good. But sometimes the tests aren't good, and in my opinion, waiting for a test and waiting for the results are a much more intense kind of worry.
Another thing I did was ask lots of questions during the u.s. Like, "What are you looking at now? Does it look normal?" It was much better than the apprehensive silence you sometimes get if the u/s tech is not chatty. Each time something looked fine, I relaxed more. That's the nice thing about u/s and fetal echo - you get the results right there.
Anyway, good luck to you. I hope you find your own peace somehow.
Wise words from another poster:
Regarding the stories about handling the stress, it warmed my heart to see the support given to each other on this site. The weeks in Feb and March were the most anxiety ridden of my life. Empty promises of “I have this feeling everything will be fine” from well-meaning friends and family did little to reassure me, and also irritated me at times. The one thing that made me feel better was one morning when I asked my husband “how are we going to handle it if we get some bad news?”. He paused and then said “I guess we’ll love him just a little more, since he’ll probably need it just a little more”. In that moment I knew that this was the most true statement I’d heard yet. And somehow that comforted me.
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