Irregular yolk sac?

Melissa
I just had an ultrasound at 6w3d because I had brown spotting this morning. They couldn't hear a heartbeat but did say the yolk sac was more oval and long and not round like normal. All they could tell me that it was a 50/50 chance of miscarriage. I'm very upset right now and not sure what to think. Anyone have any experience with this?