Sex reassignment surgery
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.
The best known of these surgeries are those that reshape the genitals, which are also known as genital reassignment surgery or genital reconstruction surgery (GRS).
The meaning of sex reassignment surgery usually differs for transwomen (male to female) rather than transmen (female to male). For transwomen, sex reassignment usually involves the surgical construction of a vagina, whereas in the case of transmen, this term may entail any of a variety of procedures, from the mastectomy (removal of the female breasts) to the shaping of a male-contoured chest to the construction of a penis. Additionally, transmen usually undergo a hysterectomy and bilateral salpingo-oophorectomy.
Chest (or "top") surgery is often the only surgical procedure female-to-male transsexuals choose to undergo, as GRS techniques for transmen are still rather unrefined and typically produce genitalia of compromised aesthetic and functional quality.
For some transwomen, facial feminization surgery and breast augmentation are also important parts of the sex reassignment process.
People who pursue sex reassignment surgery are usually referred to as transsexual; "trans" - across, through, change; "sexual" - pertaining to the sexual characteristics (not sexual actions) of a person. More recently, people pursuing SRS often identify as transgender instead of transsexual.

# Medical considerations
Those with HIV or hepatitis C may have difficulty finding a surgeon able or even willing to perform surgery because many surgeons operate out of small private clinics that cannot adequately treat potential complications in these populations. Some surgeons charge higher fees for HIV and hepatitis C positive patients (some surgeons in developing countries prefer to dispose of surgical instruments used on these populations).
Other health conditions such as diabetes, abnormal blood clotting, and obesity do not usually present a problem to experienced surgeons, but do increase the anesthetic risk and the rate of post-operative complications. Some surgeons require that severely overweight patients reduce their weight by a certain amount prior to surgery and that patients refrain from smoking for a period of time before and after surgery, although this is considered common practice regardless of the operation performed.

# Results
As a result of SRS, the person will have the external anatomical appearance and function typical of the new sex. They are unable to reproduce due to the lack of sex glands (testes or ovaries), except through prior sperm banking or embryonic freezing, which still require a receptive woman with a uterus to act as the surrogate mother (See Reproductive technology.)
Additionally, it is usually necessary for transsexual people to continue hormone replacement therapy in order to maintain their secondary sex characteristics and prevent conditions such as osteoporosis.
Transsexual people who do not undergo SRS/GRS are often called non-op, while "gender refusenik" is a slang term used among transgender people.  Possible reasons for forgoing SRS include financial, legal, and medical concerns, among others.

# Standards of care
Sex reassignment surgery can be difficult to obtain. There are very few surgeons willing to perform SRS. Most jurisdictions and medical boards require a minimum duration of psychological evaluation and living as a member of the target gender full time, sometimes called the real life experience (RLE) or real life test (RLT) before SRS is permitted. However, transsexual and transgendered people are often unable to change the listing of their sex in public records until SRS is completed, due to the laws of many jurisdictions. (See legal aspects of transsexualism.)
In many countries or areas, an individual's pursuit of SRS is often governed, or at least guided, by documents called Standards of Care for Gender Identity Disorders (SOC).  This most widespread SOC in this field is published and frequently revised by the Harry Benjamin International Gender Dysphoria Association (HBIGDA). Standards of Care usually give certain very specific "minimum" requirements as prerequisites to SRS.  For this and many other reasons, both the HBIGDA-SOC and other SOCs are highly controversial and often maligned documents among transgender patients seeking surgery.  Some alternative local standards of care exist, such as in the Netherlands, Germany, and Italy. Much of the criticism surrounding the HBIGDA-SOC applies to these as well, and some of these SOCs (mostly European SOC) are actually based on much older versions of the HBIGDA-SOC.  Other SOCs are entirely independent of the HBIGDA. The criteria of many of those SOCs are stricter than the latest revision of the HBIGDA-SOC. The majority of qualified surgeons in North America and many in Europe adhere almost unswervingly to the HBIGDA-SOC or other SOCs.

# History
The earliest known recipient of Male to Female Sex Reassignment Surgery was Lili Elbe in Berlin, in 1930-1931. This was started with the removal of the male sex organs and was carried out by Dr. Magnus Hirschfeld. Lili went on to have four more subsequent operations that included an unsuccessful ovarian transplant which resulted in death.