Introduction:

In the United States, vasectomy emerged as a popular method of permanent contraception during the 1960s. Within a decade, 750,000 men were undergoing vasectomies each year. Vasectomy rates markedly declined in the 1990s and have now leveled off at about 500,000 a year. Worldwide, millions of couples use vasectomy as a method of permanent birth control. [For non-permanent methods of birth control, including condoms, see In-Depth Report #91: Birth control options for women. ]

The procedure works by surgically interrupting the route that the sperm take from the testicles (where they are produced) to the penis. After vasectomy, the testicles still continue to generate sperm, but their movement is blocked at the site of the vasectomy. Eventually the sperm die, and the patient's body absorbs them. During sex, semen is produced in the same amount as before vasectomy, but this fluid does not contain sperm.

The testes are where sperm are manufactured in the scrotum. The epididymis is a tortuously coiled structure topping the testis, and it receives immature sperm from the testis and stores it several days. When ejaculation occurs, sperm is forcefully expelled from the tail of the epididymis into the deferent duct. Sperm then travels through the deferent duct through up the spermatic cord into the pelvic cavity, over the ureter to the prostate behind the bladder. Here, the vas deferens joins with the seminal vesicle to form the ejaculatory duct, which passes through the prostate and empties into the urethra. When ejaculation occurs, rhythmic muscle movements propel the sperm forward.

Vasectomy should not be confused with castration. It has no noticeable impact on a man's ability to perform sexually, or on his sensation of orgasm and pleasure. It does not affect the balance of male hormones, male sex characteristics, or sex drive. Testosterone continues to be produced in the testes and delivered into the bloodstream. Sperm form a very small portion of semen, so patients notice no difference in the amount of semen produced during orgasm.

The Male Reproductive Tract

The male reproductive tract performs three functions:

• It enables a man to produce offspring.
• It provides him with a supply of male hormones.
• It enables him to experience sexual pleasure.

The Traveling Sperm. The sperm's journey through the male body -- from the testes (the testicles) to the final stage (the orgasm) -- is long and complex:

• Sperm are produced in the testes at a rate of 50,000 an hour within tiny ducts called seminiferous tubules.
• Sperm do not mature in the testes. They must first pass into the epididymis, a C-shaped storage chamber adjoining the testes composed of a 20-foot coiled tube. The sperms' journey through the epididymis takes about 2 - 3 weeks. They are held here until sexual activity forces them to move on.
• When a man experiences sexual excitement, nerves stimulate the muscles in the epididymis to contract. This forces the sperm to pass into one of two rigid and wire-like muscular channels, called the vasa deferentia. (A single channel is called a vas deferens. It is the vas deferens that is cut during vasectomy.)
• Muscle contractions in the vas deferens from sexual activity propel the sperm along past the seminal vesicles, which are clusters of tissue that contribute fluid, called seminal fluid, to the sperm. The vas deferens also collects fluid from the nearby prostate gland. This mixture of various fluids and sperm is the semen.
• Each vas deferens then joins together to form the ejaculatory duct. This duct, which now contains the sperm-containing semen, passes down through the urethra. (The urethra is the same channel in the penis through which a man urinates. During orgasm, however, the prostate closes off the bladder so urine cannot enter the urethra.)
• The semen is forced through the urethra during ejaculation, the final stage of orgasm when the sperm is literally thrown out of the penis.

Having a vasectomy is a serious decision. The surgery is intended to be permanent. The great majority of men who seek a vasectomy have been married for 10 years or more. Not all are good candidates, however. It is important that both the woman and the man completely agree that they no longer want to have children. They should also agree that permanent birth control is the right decision for them. Ideally, the couple should view the operation as a mutual commitment to an already successful marriage or relationship. Vasectomy generally is not a good idea if the couple's relationship is under great stress. It is not a cure for emotional or sexual problems between a man and woman.