Triple blood tests, false positives, amnio, accuracy, questions questions....

[Britishmum]

After having an u/s on Friday to have an estimation of being 18 1/2 weeks not the 13 or so that I thought I was, (I posted about this at the weekend), I had the triple blood screening done at that time, although I now don't think that I am as far along in this pregnancy as they thought. Probably I'm closer to 17 weeks, or I'm further along by ten days or so.

The office called this morning to say that I tested as 1:10 for Downs. They've referred me for a level three u/s and possible amnio on Thursday.

I know that a lot of people have false positives. Any good links for me to read up on this? I declined the genetic counselling etc both my other pregnancies.

Also, how far do the dates affect the accuracy of the blood screening anyway? For me to be the date they said from the u/s I have to have conceived on the 5th day of bleeding, either a period or something else. It just doesnt make sense to me, so I'm sure they are out by at least 10 days either way.

Trying not to get stressed about this............just after I'd got over the fear of miscarrying again.

I'd appreciate any input. breathe breathe breathe......

[ChristaN]

Yes, how far along you are makes a big difference in whether they are reading the triple screen accurately. Basically, the levels of the stuff that they are testing your blood for will be higher the further along you are (and higher if you are carrying more than one baby - although I imagine that you would know that by now!). So, for instance, if they think that you are 13 weeks, but you are actually 17, they will be expecting the blood levels to come up like it would for a 13 weeker & they will look too high, thus something will look wrong.

I'd go ahead & have the level 3 u/s to see if they can tell better. I understand that Down's is something that they can usually pick up markers of in a level 3 u/s.

BTW, I conceived dd #2 within 2 days of my period ending while using a diaphram & spermicide. I am certain on the date b/c my dh was working in a different state at the time. Weird dates can happen! Good luck; I hope that your baby is well.

[applejuice]

Good Luck to you.

I will be praying for you.

[mistisa]

i had someone at work with the same issue and she asked for my advice whether or not to do further testing etc. what i told her was to think about what she would do with that information? would it really matter, would she terminate, etc? so, really, you need to ask yourself if further testing would ease your mind about this pregnancy or create more worries? also, you must weigh the risks of having the level 3 and amnio. i know there is a slight percentage of miscarriage with the amnio....i believe i read that in dr. sear's book. i am sure if you google it, you will come up with a ton of links, sorry, i don't have any.

i declined the testing (although they highly recommended it to me because it was FREE ) because if my baby did have DS or something, he would still be my baby and it doesn't really matter to me and i would rather not stress. (i am a big time stressor!) you know? good luck and hope it all works out.

[wombat]

I didn't bother with the blood tests due to my age. I just had a Level II ultrasound done by a perinatologist. That wasn't a big help. At 16w, the Dr. found 2 soft signs of chromosome problems - ie trisomy 21, 18 or 13 I think - cyst on brain and bright spot (calcium deposit) on heart. They scared me into having an amnio which I would never otherwise have had. The amnio found no chromosome problems. A repeat Level II u/s at 20 w found these 2 soft signs had 'resolved' - ie gone away and they decided it was probably just part of normal development.

So in terms of accuracy, the Level II u/s is better than the blood screening. But if they find any soft signs, you'll need an amnio to confirm chromosomal problems.

When deciding on these tests, ask yourself what you would do with the information? Some people may want to terminate the baby, some might just 'need' to know - ie don't like surprises and some (like me), discover there's nothing to be done with the information and wonder why in hell I bothered with it in the first place.

[Britishmum]

Thanks everyone so far.

I really really wish I'd not had the test done at all now. I only agreed as we were so much further than we thuoght and I was having blood drawn anyway for iron.... Wish I'd declined it. Sigh.

But now we've got this 'result' I feel I need to at least have the u/s, more for dh's sake than mine. I'll then take it from there. I am really not keen on an amnio, refused it for my other pregnancies, and don't want one now. Although the u/s results may alter my decision on Thursday.

It seems to me that there are a lot of factors skewing the results anyway, esp as my dates are so inconclusive.

Do they also skew the results according to the mother's age? ie, I'm 42, and they gave me a 1 in 10. If I were 35, would they give a different figure, even if the blood results were the same? Not sure if I"m making sense.....

[firefly]

Hummmm...don't know about the age thing, I was pregnant with my son when I was 24. I took the triple marker (even after my midwife told me how many false positives they see). Well it came back that I had a 1 in 100 chance of having a babe with Down's Syndrome, I guess someone who is 24 should have a 1 in 1000 chance. So on I went to a level two ultrasound where they saw that the babies hands were closed and told me this was also a sign of down's. The next step was an amnio. The doctor doing the amnio actaully looked at me and said (before the amnio) you don't have to do this your baby is probably fine. Well, I did it. Three stressful weeks later (during which I felt my ds move for the first time-and cried) we found out the baby was fine. I guess my point in sharing my story is that these tests can be inaccurate.
I'm sending you lots of good thoughts, please let us know how you are doing.
Jenn

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[starrynight]

I'm sorry that you are going through this. I know how hard it is. I had a false positive Quad screen this pregnancy and it made me a worried wreck. Our odds were 1:140, which is better than my age (1:130 - I'm 38), but scared me nevertheless. I had two level II u/s that looked normal, but I opted for the amnio anyway because u/s only picks up d/s about 50% of the time. For me, the amnio was the right decision. It was a very easy procedure and when it came back normal I felt I could finally function again - you know? At the time we decided we would not make a decision about what we would do with the results until we had them. It was just too stressful playing the "what if" game without any facts.

As far as your age, it is absolutely a factor. They use a formula when they figure out what your odds are and your age is part of that formula. The genetic counselor we spoke to said older moms get a LOT of false positives as a result of this.

Between the fact that your dates are skewed and your being older, I wouldn't be surprised if your test is another false positive. Another way to look at it is also that 1:10 odds means there's a 90% chance everything is okay. I noticed the previous post mentioned somthing about FISH. We did that, all it does is give you early results on your amnio. It doesn't involve any extra procedures. It only checks for the major chromosomally abnormalities like trisonomy 21, 18, etc. FISH was great because we found out the next day after the amnio that our son did not have d/s. The final amnio results came in 2 weeks later and confirmed the FISH.

I have to say if we decide to have more children, I would never take the Quad screen test again. Too much stress without anything conclusive.

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[Britishmum]

What's funny about the age thing was that I only turned 42 last week, so according to one table I found on the web, it supposedly increased my chances of Downs from something like 1:60 to 1:45. Therefore if I'd had the test done last week, the odds they quoted me would have sounded much better.

The dates they submitted with the test are definitely wrong, I know that for sure, but I am not certain which way, although I have a gut feeling that I"m not as far as they say.

Maybe I"m clutching at straws, but both these factors make me feel somewhat more positive.

Of course, today dd#1 spent much of the day cuddling me and talkign to the baby, telling it how much she loves it. Which was rather poignant.

When I lost the last baby before Christmas I had a gut feeling that there was something wrong. This time, aside from the weird dating, I didnt have that feeling. I'm tring to use all these thigns to stop myself from getting stressed about it and to look at it positively. And as someone said, even if it was truly a one in ten, that is nine chances that all is fine........

[starrynight]

my~hearts~light -
False positive, false negative, etc. is the way everybody has described it to me from the genetic counselor to the perinatologist to my midwife. So that's the language I'm using too.

As far as the FISH, maybe there is more than one type of FISH analysis associated with an amnio? I just had this done a couple months ago, and they definitely called the early result test a FISH. They must use this test in other ways too.

As far as your doing the triple screen again, if it worked for you then great! I know many people who have had done it with every pregnancy and were happy with it. For me, it was a nightmare that I don't care to repeat.....

[doctorjen]

The age used to calculate risk is the expected age at the time of delivery, not the age at the time of the test. So your risk doesn't change from week to week.
Having a level 2 ultrasound which shows no physical abnormalities reduces the triple screen risk by 50%, so a normal ultrasound would reduce your risk to 1 in 20.
If the baby is younger than thought, a screen showing increased risk is more likely. Generally, being within a week doesn't make much difference, but more than that may.
Age is factored into the formula that gives risk, so a 42 year old has a much higher risk of a screen showing increased risk than a 24 year old.
Triple screens can be recalculated using different dates, and may significantly change. If you and your midwife really feel the baby is just 17 weeks, perhaps ask to have the triple screen recalculated using that date.

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[Britishmum]

Some good news today! The FISH test came back with no abnormalities for chromosomes 13,18 and 21. I'm still nervous, waiting on the full amnio result, but feel very much more positive today.

Thanks so much everyone for your support. It's been tough making these decisions and trying to come to terms with what this all may mean.

[starrynight]

That's awesome news!!! I'm sure your full amnio will be fine too. I think it's very rare that they differ. I know I felt so much better when we got our FISH results. I cried with relief I was so happy!

[Britishmum]

Thanks, Starrynight! I still shake when I think about answering the phone. Taking the call with two toddlers crawling over me was difficult, and I didnt ask the quesitons I should have asked.

Like, if I was called in specifically for a high chance of Downs, which the FISH tells me the baby doesnt have, what is the chance that he/she has another chromosome abnormality. I think I drove them nuts with my drive to get statistics, but they drove me nuts refusing to give me specific answers!

Eg, if they have my due date significantly wrong (whcih I'm convinced they do) how did that alter the odds from the AFP. They kept telling me it didnt matter, but it did to me! In fact, once I got an answer, it seemed that the statistic went from 'more than one in ten' to 'about one in seventy-five' if I was right and they were wrong about my due date. A huge difference, imo!

She did tell me that there is a 0.3% chance of the FISH being wrong, but I didnt find out what the chances are statistically of something coming up on the other 16 or so abnormalities the amnio tests for.

Still, I'm a lot more confident now and able to focus a little more on other things. Which is a good thing as I have a huge work deadline for Friday and haven't even opened the document since I got the first phone call about the AFP!

[2+twins]

I just wanted to add that every one of my friends who have consented to the triple screen test have gotten back false positives. EVERY SINGLE ONE! I know this doesn't mean there aren't true positives, but there are a great deal of false ones out there. There are also false negatives. This is one test with no guarantees based on test results. My thoughts are with you.

[starrynight]

Britishmum-
I hear you about shaking when the phone rings! I was the same way. In fact, we got our final results on the day of my son's third birthday party. I was so worried they'd call me during the party, but on the other hand I didn't want to turn the ringer off because I *needed* to know. They actually called right after the party was over and it was good news so that was great.

As far as your question about other chromosomal abnormalities, I think my genetic counselor told me after the FISH that my odds at that point of any other abnormalities coming up were the same as anyone else and no longer elevated, since d/s was the thing the Quad screen had picked up on. I could be wrong about this, and if anyone knows better I hope they'll jump in here. She told me this at some point and I could have sworn it was right after the FISH (since there would be no need to tell me this after the full amnio came back normal.)

I would think them having your due date significantly wrong would definitely effect the odds they gave you. Frankly, all those statistics drove me nuts. I felt like everything was so wishy washy and I just wanted some FACTS - you know?

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From what I understand the risk of other chromosomal abnormalities is still there. IE, if your triscreen came back funny and they did a short versions test and long version they only look for a few things on the short. BUT other things can make a triscreen come back funny so until they do a full analysis there is still a chance. Then again, after the full panel is done there is STILL a chance. Afterall, they can test your chromosomes instead OR they can simply miss something. It's easier than you might think. Deletions are almost always missed on amnio unless they are HUGE and super obvious. My DD has a HUGE deletion but it was not seen on the amnio. Because huge in terms of genes is barely noticable to the naked eye (which is what your relying on with lab techs). My advice is to keep it in your mind and try to make peace with that possibility. Then be glad and blessed when your child is perfect and healthy!