I am about 5 weeks pregnant. Start of last period was Nov. 4, 2014. Had beta testing done on Dec. 11 which was at 132, done again on Dec 15 and it was at 919. Also had a vaginal ultrasound done on this day and it didn't show anything. Had beta done again on Dec 17 and it was 2729, vaginal ultrasound done the next day showed only a sac...with no embryo/baby inside. Is it normal not to see anything in the sac at this point in the pregnancy (about 5 weeks)? My OB is concerned that is could be ectopic, he believes that with the beta levels he should be able to see something in the sac already. But then again he also said that since my beta levels keep increasing that doesn't usually indicate an ectopic pregnancy. He is advising me not to get on a plane and travel home for the holidays in case it is ectopic and something happens while im in the air. So my question is whether or not its normal not to see anything in the sac at this point and whether it would be safe to fly home.