Sterilization is a surgical technique leaving a male or female unable to procreate. It is a method of birth control.
- A vasectomy in males. The vasa deferentia, the tubes which connect the testicles to the prostate, are cut and closed. This prevents sperm produced in the testicles to be in the ejaculated semen fluid (which is mostly produced in the prostate and the seminal vesicles).
- A tubal ligation in females. The Fallopian tubes, which allow the sperm to fertilize the ovum and would carry the fertilized ovum to the uterus, are closed. This is sometimes referred to as getting one's "tubes tied."
The closing of either type of tube can be done in several different ways, some of which are more permanent or guaranteed to work than others. The tube can be
- clamped off
- cut off
- tied off
Vasectomy should not be confused with castration: vasectomy does not involve removal of the testicles and it affects neither the production of male sex hormones (mainly testosterone) nor their secretion into the bloodstream. Therefore sexual desire (libido) and the ability to have an erection and an orgasm with an ejaculation are not often affected. Similarly, in females, hormone production, libido, and the menstrual cycle are not affected by a tubal ligation.
When the vasectomy is complete, sperm can no longer exit the body through the penis and it seems that they penetrate the blood-testes barrier. Normally, the barrier keeps the immune system separate from the reproductive system. When the barrier is compromised usually by vasectomy, injury, or even a simple puncture from a biopsy, the two systems interface. This usually results in the development of anti-sperm antibodies.
In order to allow for reproduction (via artificial insemination) after vasectomy, some men opt for cryostorage of sperm before sterilization. However, the long term viability of spermatozoa in cryostorage is questionable. Although there is a procedure to reverse vasectomies using vasovasostomy (a form of microsurgery), it is not effective in many cases, and men considering vasectomies should not think of them as reversible. Various temporary male contraceptives are being researched but not yet available, such as male oral contraceptives and the intra vas device.
In animals, castration (called neutering) and salpingo-oophorectomy (removal of the ovaries and Fallopian tubes, or spaying) are used to prevent conception and, in females, heat, and to prolong the animal's life. Owners of pets such as cats and dogs are urged to have their pets spayed or neutered in order to prevent an increase in the population of stray animals, which are not taken care of and often euthanized.