Nuchal screening

Hi All,

I have been reading through the boards about the nuchal screening and I'm afraid that you all have me a little bit confused. Where I'm having this done here in England, the procedure consists of both a scan (to look at the nuchal translucency, nasal bone, presence of physcial abnormalities, etc) as well as the blood test for hormone levels. I keep reading that some of you say your doctors dont recommend this screening because of the high incidence of false positives with multiples, but I'm confused. Do you just mean that the blood tests give false positives? I cant imagine why the ultrasound itself would not be useful and informative -- it sounds really thorough. In fact, the place where I'm having this screening is pretty much the best in London for the higher level scans and invasive tests (the guy who runs the place apparently has the steadiest hands in London). Anyway, I guess I'm just looking for a little clarification as to what exactly is not recommended -- the blood tests or the ultrasound. Because if its the bloodtest, then I can take the results with a grain of salt but I would still want the ultrasound.

Thanks all

 

I did have the nuchal scan via u/s at one of my appts. But I declined the blood test. I didn't do the blood test with my singleton pregnancy as well. I had heard it was not as accurate for twins, but my peri still recommended it be done and was quite shocked when I declined the blood test. I think it is the blood test that is not as accurate for twins. I know even my cousin, who was only pregnant with a singleton, got a # on her blood test that was more indicative of Downs Syndrome, she was very worried. Her DS was born 3 years perfectly healthy. So if you do get the blood test I would definitely take the results with a grain of salt, just my 2 cents.

 

I also did the neuchal, but did not do the blood test as my OB said it would be inaccurate with twins, just as Amy described above.
So if you do it I would just keep in mind that it is not 100% :good:

 

Well, my experience from the screening and what I have researched online is that the test is comprised of both the scan of the fetus and the bloodwork. My doctor explained to me that in order for you to have the most accurate results you will need to have both the scan and the bloodwork done. That being said I think the percentage of false positive results are very low, but there is still a chance of it occuring and I know a couple of people who have had false positives.
I had originally wanted one because it was the least non invasive test that would test for downs syndrome, even though my husband and I did not have any risk factors that would indicate having a baby with chromosomal abnormalities. I actaully started to cancel the screening after hearing about the false positives stories due to the fact that I didnt want that worry or burden to affect my feelings and emotions during the pregnancy. But when I tried to cancel the nurse mentioned to me that regardless of performing the tests I could atleast have a free sono, which turned out to be a very good thing because up until that point we had no idea we were having twins. It was a very surreal and exciting day.
So bottom line is that for the most accurate results you will need both the blood work and the scan. Keep in mind that the if the test comes up positive it could be false and also that they will most likely perform an amniocentesis several weeks later for a more accurate result. And you also should think about what your options are if the tests come back positive and what you will want to do.
Good Luck!


33w1d

 

I, too, took the whole nuchal screening with a big grain of salt, having read about its inaccuracy -- especially the blood test part -- with twin pregnancies. But my tech could tell me during the ultrasound if the nuchal fold is within the normal range, which I wouldn't imagine affected by the presence of two fetuses.

 

Hi. You're talking about the AFP test. I cannot imagine turning down a test, but that's just me . I would go with what your doc suggests. I'm at NYU in NYC with a high risk ob who is excellent, and he had me do the afp blood test. By the way, all was well, no false positive.
Good luck!
Lisa
(27 weeks pg w bg twins)
QUOTE(tamaras @ Apr 13 2009, 03:13 PM) [snapback]1271219[/snapback]
I also did the neuchal, but did not do the blood test as my OB said it would be inaccurate with twins, just as Amy described above.
So if you do it I would just keep in mind that it is not 100% :good:

 

I had the nuchal screening done. My blood test came back ok and the nuchal fold came back ok on both babies, but they couldn't find a nasal bone in Baby A. Totally threw us for a loop and the stress actually sent my husband's thyroid level so high he thought he was having a heart attack and sent him to the ER. After a very stressful month, we had another ultrasound (at about 17 weeks) and they found a nasal bone. Both my boys were born healthy as could be. I wish I had NEVER done the test. Hubby finally got his thryoid level back to normal after a few months.

Good luck with whatever you decide.

 

I was told the Nuchal T blood test was accurate for twins but the AFP was not (i did not do the AFP). I had both the u/s scan and the blood test done. I am not due for a while yet but things continue to look good and it gave me peace of mind.

 

QUOTE(MarchI @ Apr 13 2009, 10:35 PM) [snapback]1271387[/snapback]
I was told the Nuchal T blood test was accurate for twins but the AFP was not (i did not do the AFP). I had both the u/s scan and the blood test done. I am not due for a while yet but things continue to look good and it gave me peace of mind.


Still all so confusing! :blink:

Ok, here is a short blurb that I found about the nuchal scan:

Yes, a nuchal translucency (NT) scan is the best screening test for Down's syndrome when you are having twins. NT scans are performed from 11 to 13 weeks + 6 days of pregnancy. The blood screening test that is offered at 16 weeks when you are expecting one baby does not work very well when there are two or more babies. This is because the blood test relies on the fact that babies with Down's syndrome tend to have higher hormones (hCG) and lower proteins (AFP) than babies without Down's. If one of your twins has Down's and the other does not, the low levels of AFP from one, for instance, will be masked by normal levels from the other.

An NT scan will measure the fluid at the back of both babies' necks so that each baby can be given its own individual risk for Down's syndrome and other chromosomal abnormalities. The NT scan will detect about 75 per cent of babies with Down's syndrome. Research shows that combining the scan with a blood test to measure two hormones hCG and PAPP-A (called the combined test) can improve the detection rate for twins, though it's important to determine at the time of the scan whether or not the twins share a placenta because the levels of PAPP-A are normally lower in twins that share a placenta.

Before deciding whether or not to have a nuchal scan for twins, you need to think very carefully about what you would do if one baby has a high risk and one a low. The only way to know for sure if your babies are unaffected by Down's is to have a CVS or amniocentesis, and the risk of miscarriage following these procedures is doubled with twins. Also, if one baby is found to be affected and not the other, you may be faced with some very difficult decisions. Of course, if the twins are identical they will either both have Down's or they will both be unaffected.

Source: http://www.babycentre.co.uk/pregnancy/antenatalhealth/scans/nuchalscantwinsexpert/



I'm not sure, but that doesnt quite sound like the same thing as an AFP. I dont know, I think I will go forward with the test regardless because my husband and I would really want to know if there was a problem. To be perfectly honest, we are not necessarily the people who would choose to go forward with the pregnancy no matter what testing revealed. I'm not sure if we could handle it so I definitely want to have all the information. But if the test is really inaccurate, then I dont want to rush into a CVS or amnio if I dont necessarily need it.

 

I am glad that you asked this question. I think it brings alot to my attention to really pay attention to what the DRs are asking for me to do.

Thanks

 

http://www.mtsinai.on.ca/PDMG/Tests/nuchal.htm

That article explains that the blood test is not accurate but for twins, so the neck measurement becomes the important factor. We wouldn't terminate but we wanted to know if we were in for any surprises. There is a chance of a false positive (downs not being picked up) but that is something we have to live with.

 

The nuchal scan basically just gives you a level of risk and lets you know whether further testing is required. But you have to ask yourself whether you'd actually do anything with the information. We opted to have the test done because we wanted to see the babies (and good thing we did! that's when we found out we had twins!), but agreed ahead of time that we probably wouldn't even pursue further testing if we were put in a higher risk category for down's syndrome. The test is just there to give you some information and help you make some decisions if something serious is detected, but I don't think it's able to give you any solid answers about anything.