I'm debating about getting an NT scan. I was worried about false positves, and have to do further testing. I'm 29 now so an amnio is not required for me and I'd really rather not do an amnio if I dont have to. Does anyone know how accurate NT's are? Anyone had a false positve?
Re: NT Scan-Thoughts??
I don't know what the false positive rate is, but I can tell you my experience. It is a risk assessment tool, not diagnostic test. You can still have a normal reading and have a baby with a genetic issue and vice versa, The amnio is the only thing that can diagnose a gentic problem.
I had the first tri screen, and the scan and blood work were fine, I was in the normal risk range. My second tri blood work came back with an elevated risk for Down Syndrome. I went in for an additional ultrasound and she checked out fine, with none of the physical markers of DS. I decided against the amnio, because of the risk of miscarriage. We were not going to terminate regardless of the diagnosis, so I kind of wish I hadn't had the blood work. It can only tell you if you are at an increased risk for your age group. They told me I had a 1:180 chance of DS, vs. 1:300 for my age group (34 yo). I lost a twin in the first trimester, so that may have thrown off my results. I know it is a tough decision, good luck!
I think it depends on what you would do with the results. For us, we didn't have any additional screening for a few reasons - First, there are a lot of chances for false positives with multiples so some of the tests might not have been accurate. Second, we wouldn't have terminated the pregnancy had the results shown an abnormality. While it would be nice to have a heads up or something just to prepare, our MFM looked for markers at our 19W growth scan and didn't see anything abnormal. He and my OB were confident that this screening was sufficient and that there's nothing for us to worry about.
The most important thing about all of that is to think about what you would do with the results and base your decision on that.
The NT scan doesn't give false positives - it is a test that just gives you probabilities, the results aren't negative nor positive.
Based on age, family history, medical history, etc. you already have a probability of your baby having certain issues - the tests just move that probability up or down. In order to actually determine if the baby has Down's, etc. you would need to have an invasive test like an amnio to give you a positive or negative in addition to the NT scan.
BTW - an amnio is never required. Regardless of your age or the results of a NT scan, you still determine if you want to risk an amnio - there are just criteria where your OB/midwife may recommend an amnio based on those factors.
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It is up to you, but we decided not too because it wouldn't change our opinion on whether or not to have the baby.
It's a personal decision though.
Thank you for all the responses! Information was very helpful. We' re deciding to do it. My love for our baby wouldnt change at all but it would be nice to know ahead of time to mentally prepare and educate myself. Also, in the event something is wrong to be referred to a high risk OB. I dont know how I'd deal finding out right after giving birth.
Thank you, and good luck to us all! This is an exciting time!!