Fluid in babies kidneys?!

Makala
I had the 2nd part of my Antony scan this past week at 21+4. The baby wasn't in a good position when they tried 2 weeks ago. Everything checked our normal except for her kidneys. The doctor said the extra fluid could go away on its own but that it's a soft marker for Down's. I am besides myself. Two weeks ago we got news that my elevated hcg levels put me at a higher risk for Down's bringing my odds from 1 in 980 to 1 in 360. 
Has anyone else has fluid in their babies kidneys and everything turned out okay??
I'm trying to stay positive and not assume the worst but I am so scared.