If it's internal they advise you to have an empty bladder if it's a tummy one they advise a full bladder, but don't worry you don't have to be on the brink of weeing yourself. LOL
Best of luck for tomorrow, my dp is actually considering paying out for a scan at eight weeks, (yippee!) I'm not gonna go on abt it cos intially he said "phffff, no way we can wait like everyone else." Lol but now he can't wait either so he's considering paying out for one. hehe! We'll see.
I dunno why I think it's a girl it's weird, but I always felt my son wld be a boy and he was, can't explain. I think it's the intial feeling before you've thought abt it too much, but time will tell an we're not gonna find out the sex so be a whole eight months, haha!