The vas deferens are thin muscular tubes that carry sperm from each testicle to the seminal vesicles and then the urethra.

Vasectomy is the surgical interruption of the vas deferens. Vasectomy prevents sperm from being released into semen during ejaculation, thus preventing pregnancy. Vasectomy may be recommended for adult men who are certain that they wish to prevent future pregnancies (permanent sterilization). Vasectomy is not recommended as a temporary or reversible procedure. Vasectomy is usually done in the surgeon's office while the patient is awake but pain-free (using local anesthesia). For a traditional vasectomy, a small incision is made in the upper part of the scrotum, under the penis. Techniques that puncture the skin instead of making an incision are also in use.

The tubes (vas deferens) are tied off and cut in two. The skin incision is stitched closed. The patient is able to return home immediately. The surgeon will check a sperm sample about 6 weeks after the vasectomy, to ensure that no sperm are present in the semen. Couples should take other steps to prevent pregnancy until the doctor confirms that vasectomy was successful.

Vasectomy is a simple, painless procedure that is very effective in preventing pregnancy. Men usually have no side effects from vasectomy, and no change in sexual performance or function.