Twin or not

Hi,

We’re having a scan on Monday because we really want to know where things stand. On the previous scan, it was clear that there was a second gestational sac. In one sac, you could already see a baby – obviously very small, but the heartbeat was already there. At the time of the scan, I was 5 weeks and 6 days pregnant. In the other sac, unfortunately, nothing was visible at that point. Now my question is: is it still possible that we’ll see a baby in that sac on Monday, or should we prepare ourselves for the possibility that the baby that should have been in that sac didn’t develop properly and isn’t there anymore?