Re: Question able possible down syndrome
It depends on what blood test she had. The Triple screen (standard) has a false positive rate of like 67%. And, it's not a test for DS, it's a test for "the increased risk of DS"....big difference) Even if you have a positive result, it just means you are at a higher risk. NO blood test can diagnose DS. There is a newer integrated quad screen (called the integrated maternal serum AFP) that checks blood levels twice during pregnancy. Once in the first trimester, once in the second. Those results are analyzed and can predict at about 90% accuracy (ie 10% false positive rate) I had the triple screen in my first pregnancy and the IMSAFP in my second. In fact, I was one of the first to have it done in this state. My results were normal, lowering my predicted risk of DS from 1/300 to 1/5000. Soooo, at 36 I was never presented with the option of an amnio (which carries a risk of 1/200 for miscarriage anyway). My baby was fine. The U/S can check for certain markers in DS (cardiac abnormalities, increase thickness in neck folds, length of long bones in legs etc), but it cannot diagnose or rule out with 100% Even if all markers are present, a doctor cannot diagnose DS with an U/S. The ONLY way to determine for sure is an amnio or CVS (done earlier in pregnancy that amnio, but with higher risks). That looks at the actual chromosomes and can say with 100% (or 99.999%) accuracy that DS does or does not exist. The difference here is that an amnio or CVS can diagnose DS, the U/S can screen for possible markers and the blood tests screen for increased risk.
Hope this was helpful and not to confusing.