Sex reassignment surgery (SRS), gender reassignment surgery, or sex-change operation is a term for the surgical procedures by which a person's physical appearance and function of their existing sexual characteristics are altered to resemble that of the other sex. It is part of a treatment for gender identity disorder in transsexual and transgender people. It may also be performed on intersex people, often in infancy. Other terms for SRS include gender reassignment surgery, sex reconstruction surgery, genital reconstruction surgery, gender confirmation surgery, and more recently sex affirmation surgery. The commonly used terms sex change or sex change operation are considered factually inaccurate. The terms feminizing genitoplasty and masculinizing genitoplasty are used medically.

From http://en.wikipedia.org/wiki/Sex_reassignment_surgery