I have to agree with Yvette. At 5 weeks, its unlikely you would see much more then a sac. My OB won't do an ultrasound until Beta is at 1500. When are you having another done?
well how far along are you? Were your betas done two days apart. If you just had the beta the day before your 2nd beta OR you are 5 weeks pregnant, that's probably all you'd see is the gestational sac. Next week the yolk sac, fetal pole and hb start to show up.