1st Trimester Screen-Skewed Results?

Hi All,
I'm new to this board so please forgive me as I'm sure this topic has been discussed at length. I've done a lot of research online but figured the best people to talk to are those who have gone through it. I'm currently 14 weeks pregnant with naturally conceived twins. I stupidly went for the NT screen because I had no issues with my son and figured it would be the same with the twins. I am 32 years old and my results came back as:

NT: 1.0 (.91 MoM) and 1.1 (.92 MoM)
PAPP-A: .45 MoM
hCg: 1.53 MoM

My results came back with an increased risk of DS at 1:87. I'm going to see a high risk specialist in another week-but am trying to gather as much info as I can. I've read that there are lots of false positives with twins and that some doctors recommend against the blood screen portion-but I think many of the false positives are due to high hCg levels, which isn't the case here. It's my PAPP-A levels that are low. I'd appreciate any thoughts/opinions on this as I'm very anxious-and not looking forward to waiting another week for the high risk appt.

 

I wasn't given the detailed results of mine, but my odds were 1:1500. Sorry I can't help more, but I do agree with you on the false positive with twins. My Dr had warned me beforehand not to worry too much if my odds came back high...
I hope someone here can give you a better answer.

 

My very best girlfriend had identical twin boys three years ago (and now I'm having a set - weird) and had a very out of whack NT - her odds came back at 1:27 for both babies to have Downs. She debated an amnio - she and her husband were not considering termination - and did end up doing it. The babies results were normal. It did, however, turn out that they both had a heart defect - A/V defect - that is present in a high percentage of babies with Downs. It is likely that they would not have known about the problem prior to their birth had they not done the NT; since the NT did set off alarms, her peri was persistent with testing, etc. and identified the heart problem via echo at around 16 weeks or so. My friend had time to prepare herself mentally, find a cardiologist and surgeon that she was comfortable with, etc. The defect was very fixable - it did require open heart surgery at 4 months of age - which was stressful, of course - but the boys recovered quickly and are thriving today - no residual problems.

I didn't relay that story to scare you ... I had forgone the then triple screen when I was pregnant with my now four year old - I knew WAY too many people who had false positives and made themselves crazy. In addition, I had two friends with false negatives - they did not know their babies had Downs until birth. So I decided not to stress myself out - and my OB agreed - she advised that if anything looked funny on my 18 week ultrasound, that we'd do further testing (amnio at that point) - I guess looking for gastro defects, absence of nasal bone, etc. Everything was good on the ultrasound and I did not regret passing up the testing. I did, however, do the NT with my second baby - nearly a year after my friend's twins. It is my understanding that the NT is significantly more accurate, and, after witnessing her experience, I decided that I would rather be prepared at birth if there was a problem - you're crazy enough immediately postpartum, I would prefer to not searching out highly specialized medical care on the fly as well. And then I did the NT with the twins I'm pregnant with now, although my numbers all came back in the normal range (I am 36).

I will keep my fingers crossed for you that your test was just a false positive - but you might think about asking your Dr. to look for other problems if you are able to rule out Downs.

 

Hey there - sorry to hear about your (most likely) undue stress related to NT scan and FTS. Couple of thoughts:

1. The NT scan results are not affected by being PG with twins. They measure what they measure (and your two measurement seem fine to me; however, every tech has his/her own technique and MoM so take that w a grain of salt).

2. The blood tests are notoriously inaccurate in a lot of populations, for a ton of reasons. Two things to consider:

a. All they do for twins is double or halve the calculation - depending on how it's measured, they just assume that you have twice as much, or they should divide by twice as many babies. That was a poor mathematical explanation to say that basically, the blood results are WAY suspect with twins, even before (b).

b. This blood test, just like the sequential (quad) screen at 16 weeks, are designed to avoid false negatives. In other words, they generate a lot of false positives, and this is somewhat on purpose. The doctors/researchers are desperately trying to avoid "missing" the one case than they are concerned about generating unnecssary follow-ups and a lot of parental worry. (If I were a conspiracy theorist, I would vent about the fact that the high-risk OBs get a ton more amnios - and therefore a ton more $$ - as a result of this flaw, but I don't think it's anything intentional ... just the nature of the test).

Anyway ... MANY people screen falsely positive on the bloodwork side of these two tests, and again - that is somewhat by design. I was one of these with my first DS, when I was 30. We did not have the NT scan or first trimester screen (it was brand-new then and not covered by my insurance at my age), but I had a slightly + screen for Down Syndrome with my triple/quad screen (not sure exactly which test I had, it was 6 years ago). We had 3 weeks of panic and worry, but then a Level II U/S at 18 weeks that reassured us. We did not end up electing to have the amnio, but many others in our shoes did and would again.

I know it is SO hard to wait for the appointment next week. The good news is this - your NT scan results are good, and odds are that you're just one of the ones who screened wacky. And there is still time for CVS and/or amnio, so you can know FOR SURE exactly what the genetic results for both babies. I hope it doesn't come to that, for sure, but the good news is that you do still have time.

Hang in there.

 

While I know it may be difficult, I hope you find comfort in the fact that these are just odds. They do not tell you that either of the twins have DS and the odds are still in your/their favor that they don't. Also, it appears that your NT result was fine. I think the upper limit of what is considered normal is 2 point something? My doctor did tell me that the screen is less accurate multiples but still encouraged me to do it. The false positive rate with singletons is pretty high and for multiples even higher. It's apparently the 2nd trimester blood screen (quad screen) that is horribly inaccurate with multiples and I was told that I wouldn't be offered that.

Did your OB refer you to a genetic counselor? Usually they'll do that so patients can make informed decisions as to what next steps they want to take since further testing (CVS or amnio) which is the only way you can know for sure is more invasive.

I did have a false positive with my son and even after the amnio ruled out any chromosomal problems, my OB checked for other problems such as heart defects. It is very possible to have a perfectly healthy child with no problems even with skewed screening results.

 

Thanks all. My husband doesn't understand why I'm stressing so much when the odds are 98.9% in our favor. I told him that maybe if the doctor had presented it that way I wouldn't be as anxious. It was just such a surprise to get the call a week and a half later. Especially after everyone said the ultrasound itself looked great and they didn't anticipate any issues. We were referred to a high risk ob/gyn who can "do the amnio" as my doctor said. Love how they push that. Although we haven't decided yet on that route. It's too late for the CVS since I'm now in my 2nd trimester. Depending on what this doctor says I'm leaning towards just doing the big ultrasound (I'm going to push them to do it at 18 weeks) to check for markers and such. I know it isn't a diagnostic test, but I'm a little nervous about an invasive procedure-and my husband is very much against it.

 

I had a false + on one of the tests-level 2 screen ruled out problem a week later-after a week of worrying bout neural tube defects! Believe in the lots of false positives talked about here and let's hope ur babies are just fine!

 

I would try not to worry too much either. I was 35 when I got pg & 36 when I delivered. When I went for the 1st trimester screening the nuchual measurements were great. We spoke to the genetic specialist there and she told me what the "odds" were of me having a baby with Downs based on my age. I can't remember the # now but I know it worked out to 1%. When the blood test came back it showed a slightly increased risk but the % still worked out to 1%. So even though the % was the same the way she said we had an increased risk based on the bloodwork freaked me out. We didn't do the CVS or amnio. I tried to focus on the fact that the % is still so low. When we went back in the 2nd trimester the blood results came back much better like .02%. Both of our babies are fine.

 

The only tidbit I wanted to add is that I believe the NT test is more accurate than the bloodwork, esp. for twins. If the NT component of the 14 week screen was within normal range, I would worry a bit less than otherwise.

I should say that I'm very sympathetic to your concerns. With my singleton, we had our 14 week screen one day past the recommended gestational age, so we could not get an official NT measurement. The bloodwork came back with a 1:200 risk for Downs. It really surprised me, and worried me deeply. My husband and I had some very tough conversations about what we would do next. In the end, we decided not to have the amnio, because the risk of miscarriage from that was higher than the risk for Downs. We did the level 2 ultrasound, which gave us some comfort as everything seemed normal, and in the end our DS was picture perfect ;-). But, I know how much anxiety these screen results can cause. You seem to be doing all the right things, and I wish you lots of luck.

 

It sounds like you already know this, but screening tests are designed to try to identify all people who actually have the problem, and in the process they pick up many people who don't. While 1/87 sounds high, it is actually a very low when you think about it. I would be upset too, but try not to stress too much before you meet with your doctor and discuss.