This is a condition where the semen is released into the bladder during ejaculation. You could have this condition since birth or you could have developed it due to diabetes, multiple sclerosis, prostrate surgery or some medications.
Duct system obstruction
This condition accounts for 6% of the male fertility problems. There may be some obstruction in the passage of the sperm en route from the testis to the penis. This maybe in the vas, the epididymis duct. If the blockage is on both sides there will be no sperm.
This is a condition one is born with, the opening of the urethra is on the underside of the penis instead and thus the semen does not reach the penis.