Rapidly increasing hcg?!

Swathi

My doc had me take a blood test on Saturday and it showed 2870 hcg, but no sac in the ultrasound.. She told me that it might be too early to see the sac in the u/s and asked me to get another blood test done. I took a test on Monday and it was a freaking 59700 hcg!!

I'm kind of freaking out now. Anyone found such high hcg increase in 48 hrs???