Sex change

Sex Change is a term often used for sex change in humans, that is all medical procedures transgender people may pursue, or specifically to sex reassignment surgery, which usually refers to genital surgery only. It is also sometimes used for the medical procedures intersex people undergo, or, more often, are subjected to as children. "Sex change" is sometimes also used for the whole process of changing gender role and the medical procedures associated with it. Since changing of gender role, i.e. living as a woman instead of living as a man, or living as a man instead of living as a woman, is much more important to almost all transgender people than any medical procedures, this use is even more inaccurate. (Of course, medically induced changes and surgeries are often needed to make a change of gender role at all possible, both socially and legally. Also, they can have a very significant impact on the well-being of people having them.)

Many people also see "sex change" as factually inaccurate. Sex in humans is usually determined by four factors:
 * Chromosomes
 * Gonads (Ovaries and/or testicles)
 * Hormone status
 * Primary sex characteristics, sometimes also secondary sex characteristics

Not all of these factors can be changed, however: Gender reassignment is usually precedeed by a period of feminization or masculinization. This is accomplished by the use of either synthetic/natural hormones (such as estrogens, androgens, progesterones and anti-androgens) and/or through special herbs. The most common period before reassignment is two years either taking hormones and/or living 'full-time' (in the 'target gender' roll full time). The increase from the one-year by the Harry Benjamin Standards of Care had more to do with controversy surrounding a small minority of patients which proved to have regretted the transition, than the necessary shrinkage which easier facilitates the removal of male genetalia.
 * Chromosomes cannot be changed.
 * Gonads can be removed, but not replaced
 * Hormone status is easily changed
 * Existing sex characteristics can to some extent be changed; existing ones mostly through surgery, non-existing ones can be induced to grow through hormones. For example: Changing a male genital anatomy into a good or even excellent female appearing and functioning one is complicated, but entirely possible; changing a female genital anatomy into an even reasonably male appearing one however is extremely complicated and not successful very often; function is always limited.

Some transgender people refer to feelings of being like a woman trapped inside a man's body, or vice-versa. There is evidence that various physical conditions can produce this. Assuming the absolute idea that if something can be wrong with somebody, we have no problem in seeing that a person's hormones may be in disconcordance with their physical gender. Further, the natural introduction of certain hormones into the unborn child at key developmental stages can differ in as many as one in five people to produce inverted brain sex in one fifth of the population. While this is twice as common as left-handedness (and so relatively normal) for a proportion of these people it may produce effeminizing behaviour, attraction to the same sex (bi-sexual and homosexual) and in fewer still, identifying as the 'opposite' sex and the desiring to alter sex. Transwomen (born male) that have had sex reassignment surgery were found to have a smaller interstitial nucleus of the anterior hypothalimus similar to cisgendered women (though doubtless having other cerebral mental characteristics).

The use of computer "brain sex tests" is one way to get a feel for the orientation of a brain, though they can be misrepresentative by failure to account for the presence of hormones in the opposite sex brain. For example, it is unknown how much the presence of testosterone in a female brain temporarily masculizes it to some degree, thereby masking the natural gender function of the brain.

Only a small proportion of people (about 10%) enquiring after gender reassignment go on to have the operation. For anybody who is gender dysphoric, this can be an extremely stressful time in their life, the anxiety of such a radical alteration even being known to cause a high incidence of suicidal thoughts. Problems with being "between sexes" account for some of the stress, and acceptance by colleagues, family and friends no small amount of concern. Many transgender people do not need or wish to have genital surgery. Some would argue that there is an overemphasis on genitalia.