Empty gestational sac

According to my LMP I'm 8 weeks 6 days pregnant. I just went to my first appointment today and found out the gestational sac is empty, no yolk sac and fetal pole. The measurement for the gestational sac is about 20mm. I'm scheduled for another appointment next week to double check everything. I want to know if any of you mommies have experienced this, and if there's any possibility that it will turn into a viable pregnancy?