I do know that pseudo sacs can happen with ectopic pregnancies. However, I'm pretty sure that the Hcg numbers usually don't double even in that case. My ultrasound at 5 weeks only showed the sac in the uterus and a tiny yolk sac so it wouldn't surprise me if this is a totaly normal pregnancy and your next ultrasound will be more reassuring. I hope so anyways. Good luck and keep us posted.

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