With the union of a sperm and an ovum, an embryo acquires the chromosomes that determine the sex of the fetus (XX=female; XY=male). For the first 6 weeks, the sex of the fetus is not distinguishable.

At about 6 weeks gestation, ovaries begin to develop in those with two X chromosomes, and testicles develop in those with an X and Y chromosome. Sexual ambiguity may arise when additional X chromosomes are present, or the Y chromosome is not functioning correctly.

The X chromosome is the primary determinant of feminine traits. However, geneticists have noted over 200 traits that are thought to be X-chromosome linked (such as hemophilia and color blindness). In contrast, the Y chromosome has only been linked with testicular formation and the development of male secondary sexual characteristics during puberty.

As fetal development progresses through the pregnancy, problems may arise in the development of internal and/or external sexual organs. Since embryonic tissue is initially the same, with no male and/or female differentiation, such problems may cause genetic males to have "female" genital structures and genetic females to have "male" genital structures.

An example of this is true hermaphroditism. In the past, most of these individuals were raised as males since their external genitalia appeared more masculine. In fact, had early diagnosis been available, most should have been raised as females since they all developed significant breasts and many menstruated. After surgical removal of testicular tissue, some have even become pregnant and delivered normal children.

Symptoms vary according to the abnormality present. Abnormalities include:

• imperforate hymen -- An adolescent girl may complain of recurrent pelvic pain and lack of menstrual periods. Urinary retention may also occur.
• vaginal septum, complete -- An adolescent girl may have those symptoms similar to imperforate hymen. Incomplete vaginal septum may allow adequate menstrual flow, but later may cause pain with intercourse.
• menstruation, absent -- This may also be associated with this disease.

Inspection of the external genitalia, may reveal:

• one side of labia larger than the other, or unusually large on both sides
• vaginal opening extremely close to the urethra or anus
• urethra located on the clitoris
• enlarged clitoris

Examination of the vagina may reveal:

• absence of, or partially-formed, vagina
• fusion of the labia
• abnormal septum ("wall" of connective tissue) in the vaginal canal that may either partially or completely divide the vagina horizontally or vertically
• imperforate hymen (solid membrane obstructing the vaginal opening). In preadolescent girls, secretions may accumulate causing vaginal distention and a shiny, bulging protuberance at the vaginal opening. In adolescent girls, menstrual blood accumulates causing a purplish-red, bulging protuberance at the vaginal opening.

Early recognition of developmental disorders is important, particularly for those that involve sexual ambiguity.

• Surgical treatment, indicated in some cases depending upon the abnormality, is usually recommended during the neonatal/infant period. In some instances, reconstruction may be deferred until after puberty. Surgical reconstruction is done to most closely associate physical characteristics with the gender role assigned to the individual child. This is best done with the expert advice of a geneticist or other specialist after chromosomal studies are completed.
• Hormonal supplementation may also be necessary depending on the condition present.

Psychosocial support/counseling is required for the parents (and child when applicable) to address concerns and provide anticipatory guidance specific to the child's development.

Optimal outcome is based upon early identification of the abnormalities (during the neonatal period), early chromosomal studies, expert advice, and early intervention with treatment aimed at addressing physical, emotional, and social issues.

Potential complications arise if a diagnosis is made late or in error. Children with apparent gender-specific external characteristics may be found, at puberty, to have internal sexual organ functions specific to the sex opposite from which they were raised. Occasionally, these internal sexual organs are at risk for cancer and must be surgically removed around the time of puberty.

Call for an appointment with your health care provider if abnormal, observable gynecological structures are present, expected female characteristics (breasts, pubic hair) do not develop in girls at puberty, expected menstrual cycle functions do not develop in girls at puberty, or unexpected male characteristics develop in girls.

Adequate prenatal nutrition and avoiding exposure to illness, medications, and alcohol are all important for adequate fetal growth and development. Developmental disorders may still occur despite the mother's efforts to assure a healthy pregnancy. There is no current means of prevention.