My doctors told me that when they did my blood work to test for abnormalities that trysomie 18 had showed up. I have had many ultrasounds and nothing seems to be wrong in them they have lowerd my chances of the baby having it drastically but told me the only way to know for sure is a amnio they seem to be confident that every thing will be ok but im wondering how often that the ultrasounds can be wrong and if I sould go ahead with the amnio. And if it turns out the baby does have it what will her chances be?