choroid plexus cysts

We saw our midwife today. She told us everything looked fine on the ultrasound, except for some choroid plexus cysts, which can be a soft marker for trisomy 18. She really tried to tell us not to worry, but FTM over here. I'm worried. It doesn't help that I've noticed clenched fists in our ultrasounds too. 
I've researched it, read message boards, but still looking for more reassurance. Anyone have any reassuring anecdotes for this worry wart?