Retrograde ejaculation is a male genital disorder that occurs when semen which would be ejaculated via the urethra is redirected to the urinary bladder. Normally, the sphincter of the bladder contracts before ejaculation, inhibiting urination and preventing a reflux of semen into the bladder. The semen is forced to exit via the urethra, the path of least resistance. When the bladder sphincter does not function properly, retrograde ejaculation may occur. It can also be induced deliberately as a primitive form of male birth control or as part of certain alternative medicine practices. The retrograde-ejaculated semen is excreted from the bladder during the next urination.