I noticed a few years ago that I can't empty my bladder just sitting in one position. If I swivel and tilt, I can get quite a lot more out. I told the GP and she sent me for a pretty thorough investigation, which revealed... nothing. No prolapse, no blockages, nothing abnormal detected. I did however end up with a kidney infection, possibly because of the puddle of pee that never quite empties. If they don't find anything, there's not much you can do. It's still happening. I've broken our toilet seat several times because of the post-pee gymnastics.