6w4d vus-showing 2 fetuses, no bloodflow or heartbeat in one? doctor wasn't clear with us....

I am a fraternal twinless twin...I KNEW I was pregnant with twins before I even had an ultrasound.  The early 6w4d vus showed two sacs, one with a strong heartbeat and bloodflow...the other with no bloodflow and no heartbeat.  The doctor didn't really want to say it was definitely a fetus but I think it's because I mentioned my own history of being a twinless twin.  I am just curious...I know others have not seen a heartbeat in an early ultrasound and have still gone on to have a successful twin pregnancy but noone has mentioned anything about not seeing any bloodflow. Please give me a little hope or let me know if I am keeping my hopes up for nothing. <3 Thank you.

[AnnieBrooke]

At 6 weeks 4 days, both heartbeats should be apparent, unless one twin is younger than the other (not medically impossible but extremely rare.  It would require two ovulations in a short time, the second after the first had implanted).  If no blood is flowing, the second sac might never have developed farther than that.  You can hope, but I would also begin to prepare my mind for the possibility that the second was never even really an embryo.  Good luck, I hope your next ultrasound shows that the second one has developed.