A vasectomy is birth control for men. Each year, half a million men, from cocksure 21-year-olds to seasoned elderly gentlemen, are rendered sterile by a vasectomy in the United States, according to the National Institutes of Health.

Vasectomies cost between $500 and $1,000 and there are a few techniques used to perform them. In each method, the doctor severs the vas deferens the two tiny tubes, each about the diameter of a round shoelace, that route sperm from each testicle to the urethra in the penis during ejaculation .

How it's done

In the conventional procedure, the doctor locates the vas deferens by making two small incisions in the scrotum, the skin pouch that houses the testes. The vas deferens is cut, and then the doctor ties the cut ends and sews up the scrotal incisions.

In the no-scalpel procedure, the doctor feels for the vas deferens beneath the scrotal tissue, clamps it and makes a tiny puncture. This opening is then stretched wider to locate, cut and knot the two ends of the vas deferens. This newer method has been used in the United States since 1988, and produces less pain and fewer complications than conventional vasectomy, according to the National Institutes of Health.

A third variation is called an open-ended vasectomy, in which the vas deferens ends attached to the testicle are left open, and the one leading to the prostate is sealed.

Does it work?

In some cases, even vasectomies can't thwart the persistence of sperm. According to many male health centers, the failure rate of vasectomies is 1 in 4,000.

Recently, researchers from The Netherlands tested the semen of 1,000 men after their paternity pipelines were severed, and found that almost half continued to have sperm stragglers for a year after the surgery. However, no paternity was reported in this study, which appeared in the June issue of the British Journal of Urology.

Is it permanent?

Each year, life-changing events, such as divorce and remarriage , lead 50,000 men in the United States to go back under the knife to reinstate the vas deferens. Vasectomy reversal can cost $10,000 or more, and this procedure isn't usually covered by insurance, according to the Mayo Clinic.

The tiny inner channel of the vas deferens, must be re-aligned in a process that takes three to five grueling hours. The suture used to reconnect the ends is finer than a human hair and almost invisible, so surgeons need to use a powerful microscope.

The surgeon can usually tell during the surgery whether or not reversal has been a success by examining the quality of the fluid flowing from the vas deferens. Even so, patients must follow up at intervals of five weeks and at three, six and nine months to give a semen sample.

Of course, nothing indicates success better than pregnancy. About half of couples get pregnant within two years after a reversal, according to the Mayo Clinic.

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