You must have had something going on for him to request the blood work in the first place and he is probably being a good doctor and following up. I would definitely have the test and hope all will be good.
It depends on why you went to see your Doctor, if you are experiencing pain or heavy bleeding it gives a good view of the female reproductive organs and so a lot of information can be drawn from a TVUS. I hope all turns out well for you.
Angie