Retrograde ejaculation occurs when the sphincter muscle of the urinary bladder does not function properly. Thus, the seminal fluid is routed to the bladder, rather than passing through the urethra as in normal ejaculation.
Factors that may affect the function of the bladder sphincter muscle are antihypertensive drugs, benign hyperplasia of the prostate gland and nerve injury (due to multiple sclerosis, diabetes, or spinal cord injury).
Men with this condition may father children through assisted reproductive techniques. Sperm can be isolated from the urine; depending on their quality, intra-uterine insemination or in vitro fertilization may be applied. Success rates are equivalent to those obtained with the use of naturally produced semen.