Sex reassignment, sometimes colloquially called sex change, refers to the surgical changing of a transsexual human's biological sex. A transsexual is a person, female or male, who perceives his or her gender identity as incongruous with the anatomical reality and actively seeks to resolve the conflict through sex-reassignment surgery. The term transsexual is used to refer to both pre- and postoperative men and women, though once surgery is completed the new identity of male or female is preferred. Sex reassignment for transsexual humans requires various social, hormonal, legal, and surgical procedures. Social reassignment involves living and working as a member of the sex opposite from that which a person was born. In some cases, social reassignment suffices. In other cases, hormonal reassignment is required, in which hormonal therapy partially suppresses the existing phenotypic sex characteristics of the body and allows the development and maintenance of characteristics of the opposite sex. For male-to-female transsexuals, electrolysis of beard and body hair is necessary because estrogen does not stop hair growth. Also, estrogen does not elevate the pitch of the voice, although androgen lowers voice pitch in female-to-male transsexuals. In the United States, a legal change of sex involves chiefly a change in the birth certificate, but in Europe, legal reassignment is a more complex procedure. Surgery In the female-to-male transsexual, mastectomy might, for cosmetic and employment reasons, antedate surgery of the reproductive organs which involves hysterectomy (removal of the uterus) and oophorectomy (removal of the ovaries). For some female-to-male patients, subsequent phalloplasty (plastic surgery to attach a penis) is important for their body image and self-concept. Phalloplasty is sought by these transsexuals despite the possible imperfection of the organ for urination and its guaranteed imperfection for copulation. Many transsexuals use a prosthetic strap-on or glue-on penis, which can be made lifelike by a medical sculptor. The surgical technique for phalloplasty involves an attempt to create a tubular structure in a progressive series of operations in which the skin is peeled, rolled, and subsequently transplanted from the lower abdomen or inner thigh. This rolled skin is then attached in the position of a penis. The clitoris is left intact, embedded at the base of the penis, to preserve erotic sensation. In one type of procedure, the new organ is for copulation only and does not have a urinary connection, thus avoiding possible severe complications of urinary stricture and infection. In male-to-female surgery, the penis and testicles are removed and a vulva and vagina are constructed by using the skin from the penis to line a vaginal cavity, which has been surgically opened. If the penile skin is not adequate, an augmenting skin graft is used. Some male-to-female transsexuals also undergo surgery to enlarge the breasts and seek other forms of feminizing cosmetic surgery, such as rhinoplasty (nose surgery) and hip augmentation. For those patients whose vocal cords have not become permanently habituated toward a feminine register, surgery can be used to shorten the vocal cords in order to elevate the pitch of the voice. In female-to-male transsexuals, genital surgery involves no loss of erotically sensitive areas. In fact, under the influence of androgen, erotic sensitivity increases. In male-to-female transsexuals, however, genital surgery involves the loss of a great deal of erotic tissue. Whereas androgen enhances or intensifies the orgasm in the female-to-male transsexual, estrogen is antiandrogenic and diminishes or diffuses the orgasm as subjectively experienced in the male-to-female transsexual. Bodily feminization in males and virilization in females occurs naturally in certain endocrine syndromes. In such cases, however, the affected people do not request sex reassignment but, rather, want to get rid of what is experienced as unsightly and abnormal. TRANSSEXUALISM On the basis of endocrine techniques now available, it is not possible to demonstrate a difference in steroidal sex hormones from the gonads in transsexual patients and normal controls. However, transsexual patients possibly are atypical with respect to the way in which the brain's hypothalamic-releasing hormones respond to and interact with pituitary and gonadal hormones. If such evidence proves correct, the transsexual condition most likely originates during prenatal or early infantile periods. No other feasible hormonal hypothesis exists at present on the etiology of transsexualism. Also, no feasible hypothesis of a genetic component in transsexualism exists, although the most likely explanation is that the condition is determined by various, sequential factors. The developmental biographies of transsexuals vary. One type is that of effeminate males and, conversely, virilistic females. Such people have a history of active erotic imagery, if not experience, with same-sex partners from a very early age. A second type is that of a person who, even if he or she manifested no cross-gender signs in childhood and adolescence, was always secretly obsessed with being sex-reassigned; at puberty this person is erotically inert. A third type is that of a person who has a history of transvestism, manifesting two names, two wardrobes, and two personalities until middle life when, under the pressure of a major life crisis, full-blown transsexualism emerges. Sex reassignment is a method of rehabilitation in selected, relatively rare cases of severe displeasure with a person's natal gender. Before surgical means are used, one way to evaluate the probable success of sex reassignment is to spend 2 years living, working, and becoming rehabilitated as a member of the other sex. Hormonal reassignment can be reversed, but surgical reassignment cannot; therefore, if all psychological and social consequences of sex reassignment are negotiated far ahead of surgery, the chances of error are virtually eliminated. At this moment in medical history, sex reassignment is the only effective form of treatment for transsexualism. JOHN MONEY AND VIOLA G. LEWIS Bibliography: Benjamin, Harry, The Transsexual Phenomenon (1966); Feinbloom, Deborah H., Transvestites and Transsexuals (1976); Green, Richard, and Money, John, eds., Transsexualism and Sex Reassignment (1969); Hunt, Nancy, ed., Mirror Image (1978); Hutchison, John B., ed., Biological Determinants of Sexual Behavior (1978); Kando, Thomas, Sex Change (1973); Lothstein, Leslie M., Female-to-Male Transsexualism (1983); Mittwoch, Ursula, Genetics of Sex Differentiation (1973); Stoller, Robert J., Sex and Gender, 2 vols. (1976).