Vasectomy

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. Because the sperm itself makes up a very small proportion of the ejaculate, vasectomy does not affect the volume, appearance, texture or flavour of the ejaculate. 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 enter the bloodstream by penetrating the blood-testes barrier. Normally, the barrier keeps the immune system separate from the reproductive system. When the barrier is compromised 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.

Safety and effectiveness
Early failure rates of vasectomy are below 1%, but the effectiveness of the operation and rates of complications vary with the level of experience of the surgeon performing the operation and the surgical technique used. Early complications, including hematoma, infection, sperm granulomas, epididymitis-orchitis, and congestive epididymitis, occur in 1%–6% of men undergoing vasectomy. The incidence of chronic epididymal pain is poorly documented. Animal and human data indicate that vasectomy does not increase atherosclerosis and that increases in circulating immune complexes after vasectomy are transient. The weight of the evidence regarding prostate and testicular cancer suggests that men with vasectomy are not at increased risk of these cancers.

Although late failure (caused by recanalization of the vasa deferentia) is very rare, it has been documented.

Vasectomy is the most effective long-term contraceptive method, and is among the safest options for family planning. The rate of vasectomies to tubal ligations worldwide is approximately 3/10, with large variations between countries. In Britain, for example, vasectomy is more popular than tubal ligation[4].

Couples who opt for tubal ligation do so for a number of reasons, including:

Convenience of coupling the procedure with delivery at a hospital.
Refusal of the man to undergo vasectomy due to fear of possible side effects.
Couples who choose vasectomy are motivated by, among other factors:

Fear of surgery in the woman
Knowing men who have had the procedure and are satisfied with the results
A stronger motivation for sterilization in the man
The lower cost and simplicity of vasectomy
The lower mortality of vasectomy

Reversal
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 (it is permanent), but it can be more or less reversible, depending of the surgery process used.

Various temporary male contraceptives are being researched but not yet available, such as male oral contraceptives and the intra vas device. There has been at least one documented case of a vasectomy being reversed on a dog, which then fathered puppies after the reversal.

Serilization of animals
In animals, castration (removal of the testes) and salpingo-oophorectomy (removal of the ovaries and fallopian tubes), called "neutering" or "spaying" when applied to pets, are used to reduce or eliminate sexual behaviour, and to prevent conception, heat and possible uterine diseases in females, potentially prolonging an animal's lifespan. Due to the hormonal changes involved with both genders, this will definitely cause minor personality changes in the animal. When these changes are undesired, a different method of sterilization can be used, such as vasectomy in males or tubal ligation in females. A typical example of this practise is when male cats are subjected to vasectomy so that they are able to mate with females, thereby "bringing them off heat" (terminating estrus). This keeps the condition of the female from deteriorating due to the extra energy that is expended during estrus. A vasectomized male cat is called a "teaser tom" by cat breeders.

Animal control organizations urge owners who do not keep animals for the specific purpose of breeding from them to have their pets spayed or neutered in order to prevent an increase in the population of stray animals. These stray animals are often malnourished, and are frequently euthanized by animal welfare societies.