Research in the late 20th century led to a growing medical consensus that diverse intersex bodies are normal, but relatively rare, forms of human biology. Clinician and researcher
Milton Diamond stresses the importance of care in the selection of language related to intersex people:
Medical classifications Sexual differentiation The common pathway of
sexual differentiation, where a human female has an XX chromosome pair, and a male has an XY pair, is relevant to the development of intersex conditions. During fertilization, the sperm adds either an X (female) or a Y (male) chromosome to the X in the ovum. This determines the genetic sex of the embryo. During the first weeks of development, genetic male and female fetuses are "anatomically indistinguishable", with primitive gonads beginning to develop during approximately the sixth week of gestation. The gonads, in a bipotential state, may develop into either testes (the male gonads) or ovaries (the female gonads), depending on the consequent events. Up until and including the seventh week, genetically female and genetically male fetuses appear identical. At around eight weeks of gestation, the gonads of an XY embryo differentiate into functional testes, secreting testosterone. Ovarian differentiation, for XX embryos, does not occur until approximately week 12 of gestation. In typical female differentiation, the
Müllerian duct system develops into the
uterus,
fallopian tubes, and inner third of the vagina. In males, the Müllerian duct-inhibiting hormone
AMH causes this duct system to regress. Next, androgens cause the development of the
Wolffian duct system, which develops into the
vas deferens, seminal vesicles, and ejaculatory ducts. and
Quigley scale are visual rating systems that measure genital appearance. These measurement systems were satirized in the
Phall-O-Meter, created by the (now defunct) Intersex Society of North America.
Other signs In order to help in classification, methods other than a genitalia inspection can be performed. For instance, a
karyotype display of a tissue sample may determine which of the causes of intersex is prevalent in the case. Additionally, electrolyte tests, endoscopic exam, ultrasound and hormone stimulation tests can be done.
Causes Intersex can be divided into four categories which are: 46, XX intersex; 46, XY intersex; true gonadal intersex; and complex or undetermined intersex. External genitalia is masculinized congenitally when female fetus is exposed to excess androgenic environment. Hence, the chromosome of the person is of a female, the ovaries of a female, but external genitals that appear like a male. The
labia fuse, and the
clitoris enlarges to appear like a penis. The causes of this can be male hormones taken during pregnancy, congenital adrenal hyperplasia, male-hormone-producing tumors in the mother and
aromatase deficiency. Thus, the person has male chromosomes, but the external genitals are incompletely formed, ambiguous, or clearly female. This condition is also called 46, XY with undervirilization. In most cases, the cause of this condition is unknown.
Complex or undetermined intersex This is the condition of having any chromosome configurations rather than 46, XX or 46, XY intersex. This condition does not result in an imbalance between internal and external genitalia. However, there may be problems with sex hormone levels, overall sexual development, and altered numbers of sex chromosomes.
Medical interventions Rationales Medical interventions take place to address physical health concerns and psychosocial risks. Both types of rationale are the subject of debate, particularly as the consequences of surgical (and many hormonal) interventions are lifelong and irreversible. Questions regarding physical health include accurately assessing risk levels, necessity, and timing. Psychosocial rationales are particularly susceptible to questions of necessity as they reflect social and cultural concerns. There remains no clinical consensus about an evidence base, surgical timing, necessity, type of surgical intervention, and degree of difference warranting intervention. Such surgeries are the subject of significant contention due to consequences that include trauma, impact on sexual function and sensation, and violation of rights to physical and mental integrity. This includes community activism, and multiple reports by international human rights and health In the cases where gonads may pose a cancer risk, as in some cases of
androgen insensitivity syndrome, concern has been expressed that treatment rationales and decision-making regarding cancer risk may encapsulate decisions around a desire for surgical "normalization". •
Hormone treatment: There is widespread evidence of prenatal testing and hormone treatment to prevent or eliminate intersex traits, associated also with the problematization of sexual orientation and gender non-conformity. • Psychosocial support: All stakeholders support psychosocial support. A
joint international statement by participants at the Third
International Intersex Forum in 2013 sought, among other demands: "Recognition that medicalization and stigmatisation of intersex people result in significant trauma and mental health concerns. In view of ensuring the bodily integrity and well-being of intersex people, autonomous non-pathologising psycho-social and peer support be available to intersex people throughout their life (as self-required), as well as to parents and/or care providers." •
Genetic selection and terminations: The ethics of
preimplantation genetic diagnosis to select against intersex traits was the subject of 11 papers in the October 2013 issue of the
American Journal of Bioethics. There is widespread evidence of
pregnancy terminations arising from prenatal testing, as well as prenatal hormone treatment to prevent intersex traits. Behrmann and Ravitsky find social concepts of sex, gender and sexual orientation to be "intertwined on many levels. Parental choice against intersex may thus conceal biases against same-sex attractedness and gender nonconformity." along with their ethics, control and usage. "The experience of being photographed has exemplified for many people with intersex conditions the powerlessness and humiliation felt during medical investigations and interventions." •
Gender dysphoria: The
DSM-5 included a change from using gender identity disorder to gender dysphoria. This revised code now specifically includes intersex people who do not identify with their sex assigned at birth and experience clinically significant distress or impairment, using the language of
disorders of sex development. ==See also==