Brightness by babies bowel in ultrosound

I went for my 20 week ultrosound today and everything is looking great thank g-d. They noticed a bit of brightness by babies bowel and said its probably nothing but they have to let me know it can indicate a infection and a bit of a higher chance for down syndrome. They said,they see this in women at least 10 times a week and baby is always ok. I have a lot of anxiety but dont want to take blood test itll give me more anxiety. Im a healthy 26 year old and this is my first pregnancy.Did this happen to anyone else and everything was ok? Thanks.