I had my 18(2day) week ultra sound last week and they found only one artery on the umbilical cord. I am

Now 19 weeks and 1 day. I was sent to a specialist to check on the development. The specialist I saw told me they also found that I had renal pyelectasis in my 18 week ultra sound... during my visit w the specialist i had another ultra sound done and turns out the kidney actually went back down to its normal size. They expressed to me that it makes my risk for Down syndrome higher. I am worrying so much I don’t know what I’m gonna do until I get my screening results back. Has anyone been through something similar? If so, what happened? My doctor said there weren’t any other reasons to believe she would have DS but I can’t help but think the worst. She said my chances are 1 in 481.