Urinating in between ejaculations flushes the urethra of stray sperm and makes the way clear for the sperm-less pre-ejaculate fluid. If sperm remains after a prior ejaculation, then it's possible that they can enter the vagina and make their way to meet an egg. read more
After ejaculation, whether by masturbation or sex with a partner, sperm may be left over in the urethra. There have been suggestions that urinating between ejaculations helps remove leftover sperm from the urethra. read more
I am however a medical student and was curious as to whether there will be sperm in pre-ejaculate after urinating or not. For a summer class at school we are supposed to present information on a topic that hasn't been well researched. read more