Sex reassignment surgery  or SRS (also known as gender reassignment surgery , gender confirmation surgery , genital reconstruction surgery , gender-affirming surgery , or sex realignment surgery ) is the surgical procedure (or procedures) by which a transgender person's physical appearance and function of their existing sexual characteristics are altered to resemble that socially associated with their identified gender. It is part of a treatment for gender dysphoria in transgender people. Related genital surgeries may also be performed on intersex people, often in infancy. A 2013 statement by the United Nations Special Rapporteur on Torture condemns the nonconsensual use of normalization surgery on intersex people.  
The American Society of Plastic Surgeons (ASPS) calls this procedure Gender Confirmation Surgery or GCS.   Another term for SRS includes sex reconstruction surgery, and more clinical terms, such as feminizing genitoplasty or penectomy, orchiectomy, and vaginoplasty , are used medically for trans women, with masculinizing genitoplasty , metoidioplasty or phalloplasty often similarly used for trans men.
People who pursue sex reassignment surgery are usually referred to as transsexual (derived from "trans", meaning "across", "through", or "change", and "sexual", pertaining to the sexual characteristics —but not necessarily sexual actions—of a person).
While individuals who have undergone and completed SRS are sometimes referred to as transsexed individuals,  the term transsexed is not to be confused with the term transsexual, which may also refer to individuals who have not undergone SRS, yet whose anatomical sex may not match their psychological sense of personal gender identity.
Sex reassignment surgery performed on unconsenting minors (babies and children) may result in catastrophic outcomes (including PTSD and suicide—such as in the David Reimer case, following a botched circumcision) when the individual's sexual identity (determined by neuroanatomical brain wiring) is discrepant with the surgical reassignment previously imposed.  Milton Diamond at the John A. Burns School of Medicine, University of Hawaii recommended that physicians do no surgery on intersexed infants without their informed consent, assign such infants in the gender to which they will probably best adjust, and refrain from adding shame, stigma and secrecy to the issue, by assisting intersexual people to meet and associate with others of like condition. Diamond considered the intersex condition as a difference of sex development, not as a disorder. 
Scope and procedures
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)- or bottom surgery (the latter is named in contrast to top surgery , which is surgery to the breasts; bottom surgery does not refer to surgery on the buttocks in this context). However, the meaning of "sex reassignment surgery" has been clarified by the medical subspecialty organization, the World Professional Association for Transgender Health (WPATH), to include any of a larger number of surgical procedures performed as part of a medical treatment for "gender dysphoria" or "transsexualism". According to WPATH, medically necessary sex reassignment surgeries include "complete hysterectomy, bilateral mastectomy, chest reconstruction or augmentation ... including breast prostheses if necessary, genital reconstruction (by various techniques which must be appropriate to each patient ...)... and certain facial plastic reconstruction."  In addition, other non-surgical procedures are also considered medically necessary treatments by WPATH, including facial electrolysis.
A growing number of public and commercial health insurance plans in the United States now contain defined benefits covering sex reassignment-related procedures, usually including genital reconstruction surgery (MTF and FTM), chest reconstruction (FTM), breast augmentation (MTF), and hysterectomy (FTM).  In June 2008, the American Medical Association (AMA) House of Delegates stated that the denial to patients with gender dysphoria or otherwise covered benefits represents discrimination, and that the AMA supports "public and private health insurance coverage for treatment for gender dysphoria as recommended by the patient's physician."  Other organizations have issued similar statements, including WPATH, the American Psychological Association,  and the National Association of Social Workers.
Different SRS procedures
The array of medically indicated surgeries differs between trans women (male to female) and trans men (female to male). For trans women, genital reconstruction usually involves the surgical construction of a vagina, by means of penile inversion or the sigmoid colon neovagina technique; or, more recently, non-penile inversion techniques that provide greater resemblance to the genitals of cisgender women. For trans men, genital reconstruction may involve construction of a penis through either phalloplasty or metoidioplasty. For both trans women and trans men, genital surgery may also involve other medically necessary ancillary procedures, such as orchiectomy, penectomy, mastectomy or vaginectomy.
As underscored by WPATH, a medically assisted transition from one sex to another may entail any of a variety of non-genital surgical procedures, any of which are considered "sex reassignment surgery" when performed as part of treatment for gender identity disorder. For trans men, these may include mastectomy (removal of the breasts) and chest reconstruction (the shaping of a male-contoured chest), or hysterectomy and bilateral salpingo-oophorectomy (removal of ovaries and Fallopian tubes). For some trans women, facial feminization surgery, hair implants, and breast augmentation are also aesthetic components of their surgical treatment.
People with HIV or hepatitis C may have difficulty finding a surgeon able to perform successful surgery. Many surgeons operate in small private clinics that cannot treat potential complications in these populations. Some surgeons charge higher fees for HIV and hepatitis C-positive patients; other medical professionals assert that it is unethical to deny surgical or hormonal treatments to transsexuals solely on the basis of their HIV or hepatitis status.
Other health conditions such as diabetes, abnormal blood clotting, ostomies, and obesity do not usually present a problem to experienced surgeons. The conditions do increase the anesthetic risk and the rate of post-operative complications. Surgeons may require overweight patients to reduce their weight before surgery, any patients to refrain from hormone replacement before surgery, and smoking patients to refrain from smoking before and after surgery. Surgeons commonly stipulate the latter regardless of the type of operation.
Potential future advances
Medical advances may eventually make childbearing possible by using a donor uterus long enough to carry a child to term as anti-rejection drugs do not seem to affect the fetus.     The DNA in a donated ovum can be removed and replaced with the DNA of the receiver. Further in the future, stem cell biotechnology may also make this possible, with no need for anti-rejection drugs.
Standards of care
Sex reassignment surgery can be difficult to obtain, due to a combination of financial barriers and lack of providers. An increasing number of surgeons are now training to perform such surgeries. In many regions, an individual's pursuit of SRS is often governed, or at least guided, by documents called Standards of Care for the Health of Transsexual, Transgender, and Gender Nonconforming People (SOC). The most widespread SOC in this field is published and frequently revised by the World Professional Association for Transgender Health (WPATH, formerly the Harry Benjamin International Gender Dysphoria Association or HBIGDA). Many jurisdictions and medical boards in the United States and other countries recognize the WPATH Standards of Care for the treatment of transsexualism. For many individuals, these may 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) (sometimes mistakenly referred to as the real life test (RLT)) before genital reconstruction or other sex reassignment surgeries are permitted.
Standards of Care usually give certain very specific "minimum" requirements as guidelines for progressing with treatment for transsexualism, including accessing cross-gender hormone replacement or many surgical interventions. For this and many other reasons, both the WPATH-SOC and other SOCs are highly controversial and often maligned documents among transgender patients seeking surgery. Alternative local standards of care exist, such as in the Netherlands, Germany, and Italy. Much of the criticism surrounding the WPATH/HBIGDA-SOC applies to these as well, and some of these SOCs (mostly European SOC) are actually based on much older versions of the WPATH-SOC. Other SOCs are entirely independent of the WPATH. The criteria of many of those SOCs are stricter than the latest revision of the WPATH-SOC. Many qualified surgeons in North America and many in Europe adhere almost unswervingly to the WPATH-SOC or other SOCs. However, in the United States many experienced surgeons are able to apply the WPATH SOC in ways which respond to an individual's medical circumstances, as is consistent with the SOC.
Most surgeons require two letters of recommendation for sex reassignment surgery. At least one of these letters must be from a mental health professional experienced in diagnosing gender identity disorder, who has known the patient for over a year. Letters must state that sex reassignment surgery is the correct course of treatment for the patient.  
Many medical professionals and numerous professional associations have stated that surgical interventions should not be required in order for transsexual individuals to change sex designation on identity documents. However, depending on the legal requirements of many jurisdictions, transsexual and transgender people are often unable to change the listing of their sex in public records unless they can furnish a physician's letter attesting that sex reassignment surgery has been performed. In some jurisdictions legal gender change is prohibited in any circumstances, even after genital or other surgery or treatment.
Quality of life and physical health
Patients of sex reassignment surgery may experience changes in their physical health and quality of life, the side effects of sex steroid treatment. Hence, transgender people should be well informed of these risks before choosing to undergo SRS. 
Several studies tried to measure the quality of life and self-perceive physical health using different scales. Overall, transsexual people have rated their self-perceived quality of life as ‘normal’ or ‘quite good’, however, their overall score was still lower than the control group. Another study showed a similar level of quality of life in transsexual individuals and the control group. Nonetheless, a study with long-term data suggested that albeit quality of life of patients 15 years after sex reassignment surgery is similar to controls, their scores in the domains of physical and personal limitations were significantly lower.   On the other hand, research has found that quality of life of transsexual patients could be enhanced by other variables. For instance, trans men obtained a higher self-perceived health score than women because they had a higher level of testosterone than them. Trans women who had undergone face feminization surgery have reported higher satisfaction in different aspects of their quality of life, including their general physical health.
Looking specifically at transsexual’s genital sensitivities, trans men and trans women are capable of maintaining their genital sensitivities after SRS. However, these are counted upon the procedures and surgical tricks which are used to preserve the sensitivity. Considering the importance of genital sensitivity in helping transsexual individuals to avoid unnecessary harm or injuries to the genitals, allowing trans men to obtain an erection and perform the insertion of the erect penile prosthesis after phalloplasty,  the ability for transsexual to experience erogenous and tactile sensitivity in their reconstructed genitals is one of the essential objectives surgeons want to achieve in SRS   Moreover, studies have also found that the critical procedure for genital sensitivity maintenance and achieving orgasms after phalloplasty is to preserve both the clitoris hood and the clitoris underneath the reconstructed phallus.  
Erogenous Sensitivity is measured by the capabilities to reach orgasms in genital sexual activities, like masturbation and intercourse.  Many studies reviewed that both trans men and trans women have reported an increase of orgasms in both sexual activities,   implying the possibilities to maintain or even enhance genital sensitivity after SRS.
Psychological and social consequences
After sex reassignment surgery, transsexuals (people who underwent cross-sex hormone therapy and sex reassignment surgery) tend to be less gender dysphoric. They also normally function well both socially and psychologically. Anxiety, depression and hostility levels were lower after sex reassignment surgery.  They also tend to score well for self-perceived mental health, which is independent from sexual satisfaction.  Many studies have been carried out to investigate satisfaction levels of patients after sex reassignment surgery. In these studies, most of the patients have reported being very happy with the results and very few of the patients have expressed regret for undergoing sex reassignment surgery. 
Although studies have suggested that the positive consequences of sex reassignment surgery outweigh the negative consequences,  It has been suggested that most studies investigating the outcomes of sex reassignment surgery are flawed as they have only included a small percentage of sex reassignment surgery patients in their studies.  These methodological limitations such as lack of double-blind randomised controls, small number of participants due to the rarity of transsexualism, high drop-out rates and low follow-up rates, which would indicate need for continued study.
Persistent regret can occur after sex reassignment surgery. Regret may be due to unresolved gender dysphoria, or a weak and fluctuating sense of identity, and may even lead to suicide.  During the process of sex reassignment surgery, transsexuals may become victims of different social obstacles such as discrimination, prejudice and stigmatising behaviours.  The rejection faced by transsexuals is much more severe than what is experienced by LGB individuals.  The hostile environment may trigger or worsen internalised transphobia, depression, anxiety and post-traumatic stress. 
Many patients perceive the outcome of the surgery as not only medically but also psychologically important. Social support can help them to relate to their minority identity, ascertain their trans identity and reduce minority stress.  Therefore, it is suggested that psychological support is crucial for patients after sex reassignment surgery, which helps them feel accepted and have confidence in the outcome of the surgery; also, psychological support will become increasingly important for patients with lengthier sex reassignment surgery process. 
The majority of the transsexual individuals have reported enjoying better sex lives and improved sexual satisfaction after sex reassignment surgery.  The enhancement of sexual satisfaction was positively related to the satisfaction of new primary sex characteristics.  Before undergoing SRS, transsexual patients possessed unwanted sex organs which they were eager to remove. Hence, they were frigid and not enthusiastic about engaging in sexual activity. In consequence, transsexuals individuals who have undergone SRS are more satisfied with their bodies and experienced less stress when participating in sexual activity. 
Most of the individuals have reported that they have experienced sexual excitement during sexual activity, including masturbation.  The ability to obtain orgasms is positively associated with sexual satisfaction.  Frequency and intensity of orgasms are substantially different among transsexual men and transsexual women. Almost all female-to-male individuals have revealed an increase in sexual excitement and are capable of achieving orgasms through sexual activity with a partner or via masturbation,   whereas only 85% of the male-to-female individuals are able to achieve orgasms after SRS.  A study found that both transmen and transwomen reported that they had experienced transformation in their orgasms sensuality. The female-to-male transgender individuals reported that they had been experiencing intensified and stronger excitements while male-to-female individuals have been encountering longer and more gentle feelings. 
The rates of masturbation have also changed after sex reassignment surgery for both trans women and trans men. A study reported an overall increase of masturbation frequencies exhibited in most transsexual individuals and 78% of them were able to reach orgasm by masturbation after SRS.   A study showed that there were differences in masturbation frequencies between trans men and trans women, in which female-to-male individuals masturbated more often than male to female  The possible reasons for the differences in masturbation frequency could be associated with the surge of libido, which was caused by the testosterone therapies, or the withdrawal of gender dysphoria. 
Concerning transsexuals’ expectations for different aspects of their life, the sexual aspects have the lowest level of satisfaction among all other elements (physical, emotional and social levels). When comparing transsexuals with biological individuals of the same gender, trans women had a similar sexual satisfaction to biological women, but trans men had a lower level of sexual satisfaction to biological men. Moreover, trans men also had a lower sexual satisfaction with their sexual life than trans women. 
Society and culture
The Iranian government's response to homosexuality is to endorse, and fully pay for, sex reassignment surgery.  The leader of Iran's Islamic Revolution, Ayatollah Ruhollah Khomeini, issued a fatwa declaring sex reassignment surgery permissible for "diagnosed transsexuals".  Eshaghian's documentary, Be Like Others , chronicles a number of stories of Iranian gay men who feel transitioning is the only way to avoid further persecution, jail, or execution.  The head of Iran's main transsexual organization, Maryam Khatoon Molkara —who convinced Khomeini to issue the fatwa on transsexuality—confirmed that some people who undergo operations are gay rather than transsexual. 
In 2017, the United States Defense Health Agency for the first time approved payment for sex reassignment surgery for an active-duty U.S. military service member. The patient, an infantry soldier who identifies as a woman, had already begun a course of treatment for gender reassignment. The procedure, which the treating doctor deemed medically necessary, was performed on November 14 at a private hospital, since U.S. military hospitals lack the requisite surgical expertise. 
This was followed by Danish Lili Elbe in Dresden during 1930–1931. She started with the removal of her original sex organs, the operation supervised by Dr. Magnus Hirschfeld. Lili went on to have four more subsequent operations that included an unsuccessful uterine transplant, the rejection of which resulted in death. An earlier known recipient of this was Magnus Hirschfeld's housekeeper, but their identity is unclear at this time.
On 12 June 2003, the European Court of Human Rights ruled in favor of Van Kück, a German trans woman whose insurance company denied her reimbursement for sex reassignment surgery as well as hormone replacement therapy. The legal arguments related to the Article 6 of the European Convention on Human Rights as well as the Article 8. This affair is referred to as Van Kück vs Germany . 
In 2011, Christiane Völling won the first successful case brought by an intersex person against a surgeon for non-consensual surgical intervention described by the International Commission of Jurists as "an example of an individual who was subjected to sex reassignment surgery without full knowledge or consent".