The first test she mentioned is a Nuchal Fold Translucency u/s combined with an intergrated serum blood test (2 part blood test, one draw at X week and the other a few weeks later.) Those three things combined give about a 90% accuracy in detecting a genetic disorder. It is the most accurate, non-invasive genetic screening, but it is not diagnostic. Meaning, if it puts you at a higher risk, you would have to get an amnio to know 100%. If you are unlikely to terminate, personally I don't see much point in such extensive and expensive testing. The NF u/s can only been done by specialized u/s techs, most likely at a Maternal Fetal experts office. If you are "low risk", the intergated serum blood test is probably a good enough screening, though less accurate.
Yes, the 18-20 wk u/s can sometimes detect genetic complications, but not always. Not all babies with Down syndrome have visible markers via u/s. There are several things they will measure and look for, but again, no guarentees.
I have one son with Down syndrome. I did not take any genetic testing in my pg with him and nothing abnormal was detected via u/s. In fact, he wasn't even dx until he aspirated and stopped breathing when he was 3 wks old and we were life-flighted to a children's hospital.
I am 36, will be 37 at the birth. I am not planning on having the NF test or amnio. I'm on the fence about the intergrated serum test. I don't feel it is terribly reliable, but I am curious about the results nonetheless.
I have done a lot of research into genetic testing, so feel free to ask me any questions & I will try to help.