In the condition of retrograde ejaculation, semen doesn't come out of the penis during ejaculation but instead enters the bladder. During normal ejaculation, the opening of the bladder (bladder neck) closes to prevent semen from entering as it passes through the urethra. In retrograde ejaculation, the bladder opening does not close properly. As a result, sperm is allowed to enter the bladder instead of being ejected out the tip of the penis.

Retrograde ejaculation can be caused by diabetes, certain medications, and surgery to the bladder, prostate, or urethra. Occasionally, it can be a naturally occurring physical problem.

If retrograde ejaculation is caused by drugs, removal of the specific drug may resolve the condition. Because sperm enter the bladder, in some cases, semen can be extracted from a urine sample given after ejaculation for analysis.