Enlarged gestational sac?

Challen
I went in today for my first ultrasound. I'm 8.5 weeks. The ultrasound tech said I had an enlarged yoke sac, and we could barely see the baby but it was there, had a small fetal pole, and DID have a heart beat. The doctor said in most cases when the yoke sac is like this, it doesn't end well. Going back In a week to see if the baby progressed in growth. Any one have anything similar?