Is it necessary to perform ghusl and change underwear if semen is discharged onto it involuntarily?

What exits from the male organ may be semen (maniyy), pre-seminal fluid (madhiy), or prostatic fluid (wadiy). Each has its own rulings concerning the necessity of ghusl (ritual bath) or wudu (ablution), and regarding purity, impurity, how to purify clothes and body, and changing clothes.