This happened to me this evening. Had a transvaginal and an abdominal ultrasound and heartbeat clear on both.
If you had something similar did you have a healthy baby at the end of it and did you ever get to the bottom of why it happened?
Don't sugar coat it for me- I've had a worrying evening and whilst I'm feeling much more positive than I was, I never had a single bit of bleeding with my 18 month old DD.