Here's the funky part....
At the time of the u/s (5-6w), they got an HCG level-- 1880.
5-7 days later, they took another level-- 1600. That surprised me a little, as I would have thought it had dropped more significantly (esp with all the bleeding), but what do I know?
Then, 8 days after THAT, her HCG is 2400?
I don't want to get her hopes up (her MWs want her to get another u/s on Monday, which makes sense to me), but the only thing I keep thinking is that she might have lost a twin? It seems to be pretty common (has happened to two good friends of mine, and the other twin was fine). Just because it seems the levels didn't drop as quickly as I'd think, and then rose...? Not by a huge amount, but significantly (50%)?
What other explanations could there be? Do levels ever rise even after you've passed what seems like tissue? At this point, she is or would be 7.5-8.5w, if that helps.