Vasectomy is minor surgery to block sperm from reaching the semen that is ejaculated from the penis. Semen still exists, but it has no sperm in it. After a vasectomy the testes still make sperm, but they are soaked up by the body. Each year, more than 500,000 men in the U.S. choose vasectomy for birth control. A vasectomy prevents pregnancy better than any other method of birth control, except abstinence. Only 1 to 2 women out of 1,000 will get pregnant in the year after their partners have had a vasectomy.
What Happens under Normal Conditions?
Both sperm and male sex hormones are made in the paired testes. The testes are in the scrotum at the base of the penis. Sperm leave the testes through a coiled tube (the "epididymis"), where they stay until they're ready for use. Each epididymis is linked to the prostate by a long tube called the vas deferens (or "vas"). The vas runs from the lower part of the scrotum into the inguinal canal. It then goes into the pelvis and behind the bladder. This is where the vas deferens joins with the seminal vesicle and forms the ejaculatory duct. When you ejaculate, seminal fluid and seminal vesicles mix with sperm to form semen. The semen flows through the urethra and comes out the end of your penis.