It's terrible and stressful and the worst news you can hear during pregnancy.
Our dd#2 had a genetic anomaly according to an early ultrasound. Further ultrasounds found the same anomaly. After many many tests the amniocentisis finally came back clear and after that the 'anomaly' disappeared from our ultrasound. She is perfect and healthy and terribly two!
Here's a bunch of positive energy and prayers heading your way, I know how awful things like this can be, but I also know how well they can turn out. Stay positive until you have something definitive, I know that's nearly impossible, but with the energy of this board behind you, you can do it!