CAIS can only be diagnosed in normal phenotypic females. It is not usually suspected unless the menses fail to develop at puberty, or an inguinal hernia presents during premenarche. As many as 1–2% of prepubertal girls that present with an inguinal hernia will also have CAIS.

A diagnosis of CAIS or Swyer syndrome can be made in utero by comparing a karyotype obtained by amniocentesis with the external genitalia of the fetus during a prenatal ultrasound. Many infants with CAIS do not experience the normal, spontaneous neonatal testosterone surge, a fact which can be diagnostically exploited by obtaining baseline luteinizing hormone and testosterone measurements, followed by a human chorionic gonadotropin (hGC) stimulation test.

The main differentials for CAIS are complete gonadal dysgenesis (Swyer syndrome) and Müllerian agenesis (Mayer-Rokitansky-Kuster-Hauser syndrome or MRKH). Both CAIS and Swyer syndrome are associated with a 46,XY karyotype, whereas MRKH is not; MRKH can thus be ruled out by checking for the presence of a Y chromosome, which can be done either by fluorescence in situ hybridization (FISH) analysis or on full karyotype. Swyer syndrome is distinguished by poor breast development and shorter stature. The diagnosis of CAIS is confirmed when androgen receptor (AR) gene sequencing reveals a mutation, although up to 5% of individuals with CAIS do not have an AR mutation.

Up until the 1990s, a CAIS diagnosis was often hidden from the affected individual and / or family. It is current practice to disclose the genotype at the time of diagnosis, particularly when the affected girl is at least of adolescent age. If the affected individual is a child or infant, it is generally up to the parents, often in conjunction with a psychologist, to decide when to disclose the diagnosis.

Unfortunately, the number of differentials to consider for PAIS is particularly large. Prompt diagnosis is particularly urgent when a child is born with ambiguous genitalia, as some causes are associated with potentially life-threatening adrenal crises. Determination of testosterone, testosterone precursors and dihydrotestosterone (DHT) at baseline and / or after human chorionic gonadotropin (hCG) stimulation can be used to exclude such defects in androgen biosynthesis.

Approximately one half of all 46,XY individuals born with ambiguous genitalia will not receive a definitive diagnosis. Androgen receptor (AR) gene mutations cannot be found in 27% to 72% of individuals with PAIS. As a result, genetic analysis can be used to confirm a diagnosis of PAIS, but it cannot be used to rule out PAIS. Evidence of abnormal androgen binding in a genital skin fibroblast study has long been the gold standard for the diagnosis of PAIS, even when an AR mutation is not present. However, some cases of PAIS, including AR-mutant-positive cases, will show normal androgen binding. A family history consistent with X-linked inheritance is more commonly found in AR-mutant-positive cases than AR-mutant-negative cases.

The use of dynamic endocrine tests is particularly helpful in isolating a diagnosis of PAIS. One such test is the human chorionic gonadotropin (hCG) stimulation test. If the gonads are testes, there will be an increase in the level of serum testosterone in response to the hCG, regardless of testicular descent. The magnitude of the testosterone increase can help differentiate between androgen resistance and gonadal dysgenesis, as does evidence of a uterus on ultrasound examination. Testicular function can also be assessed by measuring serum anti-Müllerian hormone levels, which in turn can further differentiate PAIS from gonadal dysgenesis and bilateral anorchia.

Another useful dynamic test involves measuring the response to exogenous steroids; individuals with AIS show a decreased response in serum sex hormone binding globulin (SHBG) after a short term administration of anabolic steroids. Two studies indicate that measuring the response in SHBG after the administration of stanozolol could help to differentiate individuals with PAIS from those with other causes of ambiguous genitalia, although the response in individuals with predominantly male phenotypes overlaps somewhat with the response in normal males.

Individuals with CAIS are raised as females. They are born phenotypically female and almost always have a heterosexual female gender identity; the incidence of homosexuality in women with CAIS is thought to be less than unaffected women. However, at least two case studies have reported male gender identity in individuals with CAIS.

Gonadectomy at time of diagnosis is the current recommendation for PAIS if presenting with cryptorchidism, due to the high (50%) risk of germ cell malignancy. The risk of malignancy when testes are located intrascrotally is unknown; the current recommendation is to biopsy the testes at puberty, allowing investigation of at least 30 seminiferous tubules, with diagnosis preferably based on OCT3/4 immunohistochemistry, followed by regular examinations. Hormone replacement therapy is required after gonadectomy, and should be modulated over time to replicate the hormone levels naturally present in the body during the various stages of puberty. Artificially induced puberty results in the same, normal development of secondary sexual characteristics, growth spurt, and bone mineral accumulation. Women with PAIS may have a tendency towards bone mineralization deficiency, although this increase is thought to be less than is typically seen in CAIS, and is similarly managed.

Common hormonal test include determination of FSH and testosterone levels. A blood sample can reveal genetic causes of infertility, e.g. Klinefelter syndrome, a Y chromosome microdeletion, or cystic fibrosis.

Ultrasonography of the scrotum is useful when there is a suspicion of some particular diseases. It may detect signs of testicular dysgenesis, which is often related to an impaired spermatogenesis and to a higher risk of testicular cancer. Scrotum ultrasonography may also detect testicular lesions suggestive of malignancy. A decreased testicular vascularization is characteristic of testicular torsion, whereas hyperemia is often observed in epididymo-orchitis or in some malignant conditions such as lymphoma and leukemia. Doppler ultrasonography useful in assessing venous reflux in case of a varicocele, when palpation is unreliable or in detecting recurrence or persistence after surgery, although the impact of its detection and surgical correction on sperm parameters and overall fertility is debated.

Dilation of the head or tail of the epididymis is suggestive of obstruction or inflammation of the male reproductive tract. Such abnormalities are associated with abnormalities in sperm parameters, as are abnormalities in the texture of the epididymis. Scrotal and transrectal ultrasonography (TRUS) are useful in detecting uni- or bilateral congenital absence of the vas deferens (CBAVD), which may be associated with abnormalities or agenesis of the epididymis, seminal vesicles or kidneys, and indicate the need for testicular sperm extraction. TRUS plays a key role in assessing azoospermia caused by obstruction, and detecting distal CBAVD or anomalies related to obstruction of the ejaculatory duct, such as abnormalities within the duct itself, a median cyst of the prostate (indicating a need for cyst aspiration), or an impairment of the seminal vesicles to become enlarged or emptied.

Due to the inability of the streak gonads to produce sex hormones (both estrogens and androgens), most of the secondary sex characteristics do not develop. This is especially true of estrogenic changes such as breast development, widening of the pelvis and hips, and menstrual periods. As the adrenal glands can make limited amounts of androgens and are not affected by this syndrome, most of these persons will develop pubic hair, though it often remains sparse.

Evaluation of delayed puberty usually reveals elevation of gonadotropins, indicating that the pituitary is providing the signal for puberty but the gonads are failing to respond. The next steps of the evaluation usually include checking a karyotype and imaging of the pelvis. The karyotype reveals XY chromosomes and the imaging demonstrates the presence of a uterus but no ovaries (the streak gonads are not usually seen by most imaging). Although an XY karyotype can also indicate a person with complete androgen insensitivity syndrome, the absence of breasts, and the presence of a uterus and pubic hair exclude the possibility. At this point it is usually possible for a physician to make a diagnosis of Swyer syndrome.

The consequences to the girl with XX gonadal dysgenesis:

1. Her gonads cannot make estrogen, so her breasts will not develop and her uterus will not grow and menstruate until she is given estrogen. This is often given through the skin now.

2. Her gonads cannot make progesterone, so her menstrual periods will not be predictable until she is given a progestin, still usually as a pill.

3. Her gonads cannot produce eggs so she will not be able to conceive children naturally. A woman with a uterus but no ovaries may be able to become pregnant by implantation of another woman's fertilized egg (embryo transfer).

Swyer syndrome represents one phenotypic result of a failure of the gonads to develop properly, and hence is part of a class of conditions termed gonadal dysgenesis. There are many forms of gonadal dysgenesis.

Swyer syndrome is an example of a condition in which an externally unambiguous female body carries dysgenetic, atypical, or abnormal gonads. Other examples include complete androgen insensitivity syndrome, partial X chromosome deletions, lipoid congenital adrenal hyperplasia, and Turner syndrome.

Identification of 45,X/46,XY karyotype has significant clinical implications due to known effects on growth, hormonal balance, gonadal development and histology. 45,X/46,XY is diagnosed by examining the chromosomes in a blood sample.

The age of diagnosis varies depending on manifestations of disease prompting reason for cytogenetic testing. Many patients are diagnosed prenatally due to fetal factors (increased nuchal fold, or abnormal levels of serum), maternal age or abnormal ultrasounds, while others will be diagnosed postnatal due to external genital malformation. It is not uncommon for patients to be diagnosed later in life due to short stature or delayed puberty, or a combination of both.

45,X/46,XY mosaicism can be detected prenatally through amniocentesis however, it was determined that the proportion of 45,X cells in the amniotic fluid cannot predict any phenotypic outcomes, often making prenatal genetic counselling difficult.

The most common diagnostic dilemma in otherwise normal boys is distinguishing a retractile testis from a testis that will not descend spontaneously into the scrotum. Retractile testes are more common than truly undescended testes and do not need to be operated on. In normal males, as the cremaster muscle relaxes or contracts, the testis moves lower or higher ("retracts") in the scrotum. This cremasteric reflex is much more active in infant boys than older men. A retractile testis high in the scrotum can be difficult to distinguish from a position in the lower inguinal canal. Though there are various maneuvers used to do so, such as using a cross-legged position, soaping the examiner's fingers, or examining in a warm bath, the benefit of surgery in these cases can be a matter of clinical judgment.

In the minority of cases with bilaterally non-palpable testes, further testing to locate the testes, assess their function, and exclude additional problems is often useful. Pelvic ultrasound or magnetic resonance imaging performed and interpreted by a radiologist can often, but not invariably, locate the testes while confirming absence of a uterus. A karyotype can confirm or exclude forms of dysgenetic primary hypogonadism, such as Klinefelter syndrome or mixed gonadal dysgenesis.

Hormone levels (especially gonadotropins and AMH) can help confirm that there are hormonally functional testes worth attempting to rescue, as can stimulation with a few injections of human chorionic gonadotropin to elicit a rise of the testosterone level. Occasionally these tests reveal an unsuspected and more complicated intersex condition.

In the even smaller minority of cryptorchid infants who have other obvious birth defects of the genitalia, further testing is crucial and has a high likelihood of detecting an intersex condition or other anatomic anomalies. Ambiguity can indicate either impaired androgen synthesis or reduced sensitivity. The presence of a uterus by pelvic ultrasound suggests either persistent Müllerian duct syndrome (AMH deficiency or insensitivity) or a severely virilized genetic female with congenital adrenal hyperplasia. An unambiguous micropenis, especially accompanied by hypoglycemia or jaundice, suggests congenital hypopituitarism.

Surgery is sometimes performed to alter the appearance of the genitals. However many surgeries performed on intersex people lack clear evidence of necessity, can be considered as mutilating, and are widely considered to be human rights violations when performed without the informed consent of the recipient.

A problem for people with penile agenesis is the absence of a urinary outlet. Before genital metamorphosis, the urethra runs down the anal wall, to be pulled away by the genital tubercle during male development. Without male development this does not occur. The urethra can be surgically redirected to the rim of the anus immediately after birth to enable urination and avoid consequent internal irritation from urea concentrate. In such cases, the perineum may be left devoid of any genitalia, male or female.

A working penis transplant on to an agenetic patient has never been successful. Only one major penis graft was successfully completed. This occurred in China and the patient shortly rejected it on psychological grounds. However a full female or agenetic to male transplant is not yet facilitated to fulfil full reproductive functions.

On March 18, 2013, it was announced that Andrew Wardle, a British man born without a penis, was going to receive a pioneering surgery to create a penis for him. The surgeons hope to "fold a large flap of skin from his arm — complete with its blood vessels and nerves — into a tube to graft onto his pubic area." If the surgery goes well, the odds of starting a family are very good.

Because of the inability of the streak gonads to produce sex hormones (both estrogens and androgens), most of the secondary sex characteristics do not develop. This is especially true of estrogenic changes such as breast development, widening of the pelvis and hips, and menstrual periods. Because the adrenal glands can make limited amounts of androgens and are not affected by this syndrome, most of these girls will develop pubic hair, though it often remains sparse.

Evaluation of delayed puberty usually reveals the presence of pubic hair, but elevation of gonadotropins, indicating that the pituitary is providing the signal for puberty but the gonads are failing to respond. The next steps of the evaluation usually include checking a karyotype and imaging of the pelvis. The karyotype reveals XX chromosomes and the imaging demonstrates the presence of a uterus but no ovaries (the streak gonads are not usually seen by most imaging). At this point it is usually possible for a physician to make a diagnosis of XX gonadal dysgenesis.

The most common presentation of testicular cancer is a hard, painless lump which can be felt on one of the testis. It is either noticed by a clinician during a routine examination, or the patient themselves. Risk factors for TC include:

- Cryptorchidism

- Family history

- Previous testicular cancer

- Being white

The diagnosis is confirmed in different ways. An ultrasound scan can be used to diagnose to a 90-95% accuracy. Bloods can also be taken to look for elevated tumour markers which is also used to analyse the patient’s response to treatment. 80% of testicular cancer cases are from the 20-34 year old age range

During embryogenesis, without any external influences for or against, the human reproductive system is intrinsically conditioned to give rise to a female reproductive organisation.

As a result, if a gonad cannot express its sexual identity via its hormones—as in gonadal dysgenesis—then the affected person, no matter whether their chromosomes are XY or XX, will develop external female genitalia. Internal female genitalia, primarily the uterus, may or may not be present depending on the cause of the disorder.

In both sexes, the commencement and progression of puberty require functional gonads that will work in harmony with the hypothalamic and pituitary glands to produce adequate hormones.

For this reason, in gonadal dysgenesis the accompanying hormonal failure also prevents the development of secondary sex characteristics in either sex, resulting in a sexually infantile female appearance and infertility.

This condition will occur if there is an absence of both Müllerian inhibiting factor and testosterone. The absence of testosterone will result in regression of the Wolffian ducts; normal male internal reproductive tracts will not develop. The absence of Müllerian inhibiting factor will allow the Müllerian ducts to differentiate into the oviducts and uterus. In sum, this individual will possess female-like internal and external reproductive characteristics, lacking secondary sex characteristics. The genotype may be either 45,XO, 46,XX or 46,XY.

Growth of the penis both before birth and during childhood and puberty is strongly influenced by testosterone and, to a lesser degree, the growth hormone. However, later endogenous hormones mainly have value in the treatment of micropenis caused by hormone deficiencies, such as hypopituitarism or hypogonadism.

Regardless of the cause of micropenis, if it is recognized in infancy, a brief course of testosterone is often prescribed (usually no more than 3 months). This usually induces a small amount of growth, confirming the likelihood of further growth at puberty, but rarely achieves normal size. No additional testosterone is given during childhood, to avoid unwanted virilization and bone maturation. (There is also some evidence that premature administration of testosterone can lead to reduced penis size in the adult.)

Testosterone treatment is resumed in adolescence only for boys with hypogonadism. Penile growth is completed at the end of puberty, similar to the completion of height growth, and provision of extra testosterone to post-pubertal adults produces little or no further growth.

Central to the cause of irreversible TDS are disruptions to early fetal testes development. This has both genetic, environmental, and lifestyle components, however the rapid increase in the incidence of the disorders associated with TDS in the last decades indicates that it is under a powerful environmental influence. The fetal origins of TDS are reinforced by the high incidence of TDS disorders found occurring together in one individual.

People with either penile agenesis or testicular agenesis, but not both, usually continue as males throughout their lives. Historically, people with both penile and testicular agenesis were raised as females and eventually underwent sex reassignment surgery, despite having a normal 46,XY male karyotype and no female sexual characteristics. This practice was controversial, and many individuals decided to live as males again when they reached puberty or their early twenties. The New Zealand sexologist John Money was the principle theorist who argued that boys born without an "adequate" penis, or who lost their penis in an accident, should be raised as sex reassigned girls. The book "As Nature Made Him" chronicles the disastrous results of the application of Money's theories in the Bruce/Brenda case. The anatomy underlying the failure of these cases is not well understood. In most males, the development of the embryo into a female is prevented by Anti-Müllerian hormones. These hormones are commonly believed to be created in the testes, but they nevertheless still appear to be produced in male embryos lacking testes.

Hormone replacement therapy with estrogen may be used to treat symptoms of hypoestrogenism in females with the condition. There are currently no known treatments for the infertility caused by the condition in either sex.

Because hormone treatment rarely achieves average size, several surgical techniques similar to phalloplasty for penis enlargement have been devised and performed; but they are not generally considered successful enough to be widely adopted and are rarely performed in childhood.

In extreme cases of micropenis, there is barely any shaft, and the glans appears to sit almost on the pubic skin. From the 1960s until the late 1970s, it was common for sex reassignment and surgery to be recommended. This was especially likely if evidence suggested that response to additional testosterone and pubertal testosterone would be poor. With parental acceptance, the boy would be reassigned and renamed as a girl, and surgery performed to remove the testes and construct an artificial vagina. This was based on the now-questioned idea that gender identity was shaped entirely from socialization, and that a man with a small penis can find no acceptable place in society.

Johns Hopkins Hospital, the center most known for this approach, performed twelve such reassignments from 1960 to 1980, most notably that of David Reimer (whose penis was destroyed by a circumcision accident), overseen by John Money. By the mid-1990s, reassignment was less often offered, and all three premises had been challenged. Former subjects of such surgery, vocal about their dissatisfaction with the adult outcome, played a large part in discouraging this practice. Sexual reassignment is rarely performed today for severe micropenis (although the question of raising the boy as a girl is sometimes still discussed.) (See "History of intersex surgery" for a fuller discussion.)

A treatment option for micropenis is the insertion of a subcutaneous soft silicone implant under the penile skin. The procedure was developed by urologist James J. Elist.

Treatment includes androgen (testosterone) supplementation to artificially initiate puberty, testicular prosthetic implantation, and psychological support. Gender Dysphoria may result in anorchic individuals who are assigned male at birth and raised as male despite lacking the necessary masculinizing hormones during prenatal, childhood, and adolescent development. Anorchic individuals who have a female identity may be administered estrogen alone in place of testosterone as no androgen blockers are necessary due to the lack of gonads.

Anorchia (or anorchism) is an XY disorder of sex development in which individuals have both testes absent at birth. Within a few weeks of fertilization, the embryo develops rudimentary gonads (testes), which produce hormones responsible for the development of the reproductive system. If the testes fail to develop within eight weeks, the baby will develop female genitalia (see Swyer syndrome). If the testes begin to develop but are lost or cease to function between eight and 10 weeks, the baby will have ambiguous genitalia when it is born. However, if the testes are lost after 14 weeks, the baby will have partial male genitalia with the notable absence of gonads.

Tests include observable lack of testes, low testosterone levels (typical female levels), elevated follicle stimulating hormone and luteinizing hormone levels, XY karyotype, ultrasound or magnetic resonance imaging showing absent gonadal tissue, low bone density, low anti-Müllerian hormone levels, and surgical exploration for evidence of male gonadal tissue.

Between 5 and 10 percent of women with POF may become pregnant. Currently no fertility treatment has officially been found to effectively increase fertility in women with POF, and the use of donor eggs with in-vitro fertilization (IVF) and adoption are popular as a means of achieving parenthood for women with POF. Some women with POF choose to live child-free. (See impaired ovarian reserve for a summary of recent randomized clinical trials and treatment methods.)

Currently New York fertility researchers are investigating the use of a mild hormone called dehydroepiandrosterone (DHEA) in women with POF to increase spontaneous pregnancy rates. Published results from studies conducted on DHEA have indicated that DHEA may increase spontaneously conceived pregnancies, decrease spontaneous miscarriage rates and improve IVF success rates in women with POF.

Additionally, over the last five years a Greek research team has successfully implemented the use of dehydroepiandrosterone (DHEA) for the fertility treatment of women suffering with POF.The majority of the patients were referred for donor eggs or surrogacy, however after a few months of DHEA administration, some succeeded in getting pregnant through IVF, IUI, IUTPI or natural conception. Many babies have been born after treatment with DHEA.

Ovarian tissue cryopreservation can be performed on prepubertal girls at risk for premature ovarian failure, and this procedure is as feasible and safe as comparable operative procedures in children.