I too have a weak bladder and every time I have been fir an ultrasound I have to empty my bladder and have an internal scan. For a normal scan u lie on a bed and pull ur trousers/ skirt down to ur 'hairline', they then put the cold jelly on ur belly and using the scanner thing press quite hard down to have a look. Usually u don't see anything as the screen is turned away from u.
If u are like me and they can't see enough and have to do an internal, don't worry about it. They ask u to pee and strip off ur bottom half and give a gown to put on. They use a small probe like thing which is covered in jelly stuff, it doesn't hurt at all but can be abit uncomfortable when they look at the ovaries.
Don't worry about having either scan done as it is nice and easy, good luck Hun xx