Defects of the external genital organs (penis, testes, or clitoris) usually result from abnormal levels of sex hormones in the fetus before birth. Congenital adrenal hyperplasia (a metabolic disorder) and chromosomal abnormalities commonly cause genital defects.
A child may be born with genitals that are not clearly male or female (ambiguous genitals, or intersex state). Most children with ambiguous genitals are pseudohermaphrodites—that is, they have ambiguous external genital organs but either ovaries or testes (not both). Pseudohermaphrodites are genetically male or female.
Diagnostic evaluation of a child with ambiguous genitals includes physical examination and blood tests to analyze the chromosomes (the XY chromosome pattern is male and the XX chromosome pattern is female) and hormone levels (pituitary hormones and male sex hormones, or androgens, such as testosterone). X-rays and ultrasonography of the pelvis may help identify internal sex organs. Treatment with testosterone may help enlarge the penis so that assignment to a male sex is more realistic.
Most experts believe that the child's sex must be assigned quickly. Otherwise, bonding by the parents to the child may become more difficult, and the child may develop a gender identity disorder (see Sexuality: Gender Identity). The decision to assign gender to a baby with ambiguous genitals depends on several factors. They include how much testosterone the fetus was exposed to, what the potential for sexual function is (as determined, for example, by how much erectile tissue the baby has), and the potential for reproduction. Environmental and psychologic factors, such as parents' perception of gender, also affect the decision. Surgery to correct the ambiguous genitals can be performed later, especially if the defect is complex. The underlying problem causing pseudohermaphroditism may also need treatment.
Male Genital Defects
Male and female sex organs develop from similar tissue in the embryo. When acted on by high levels of testosterone before birth (as in a normal male fetus), the genitals become the penis, scrotum, and penile urethra. Low or absent testosterone levels lead to the development of a clitoris, labia majora, and separate vaginal and urethral canals. Intermediate levels of testosterone cause ambiguous genitals: Genetic males have a small penis and testes that remain in the abdomen instead of descending into the scrotum (undescended testes, also known as cryptorchidism), and genetic females have an enlarged clitoris with fused labia. The appearance of the genitals in both sexes is very similar.
Pseudohermaphroditism in the male (better termed undervirilized 46,XY intersex), results in a genetic male who has female-appearing external genitals but has undescended testes. Pseudohermaphroditism may be caused by a prenatal deficiency of male sex hormones (androgens), an inability of the body's tissues to respond to androgens, exposure to female sex hormones (estrogens), or a chromosomal abnormality (see Miscellaneous Disorders in Infants and Young Children: Undescended and Retractile Testes).
After they develop, the testes produce most of the male body's androgens. Absent or underdeveloped testes cause androgen deficiency.
Androgen deficiency during childhood causes incomplete sexual development. An affected boy retains a high-pitched voice and has poor muscle development for his age. The penis, testes, and scrotum are underdeveloped. Pubic and underarm hair is sparse, and the arms and legs are abnormally long.
Androgen deficiency can be treated with testosterone. The testosterone is usually given by injection or through a skin patch. Injection and skin application cause fewer side effects than taking testosterone by mouth. Testosterone stimulates growth, sexual development, and fertility.
Female Genital Defects
Female pseudohermaphroditism (also called virilization or overvirilized 46,XX intersex) is caused by exposure to high levels of male hormones. The most common cause is enlarged adrenal glands (congenital adrenal hyperplasia) that overproduce male hormones because an enzyme is missing. The male hormones cannot be converted to female hormones as occurs in normal females. Sometimes, male hormones enter the placenta from the mother's blood. For example, the mother may have been given drugs such as progesterone to prevent a miscarriage (some progesterone is changed into the male hormone testosterone by the fetus) or the mother may have had a hormone-producing tumor, although this is much less common.
A female pseudohermaphrodite has female internal organs but has an enlarged clitoris that resembles a small penis.
If the child is assigned to the female gender, surgery is performed to create female-appearing genitals. This surgery can include reduction of the clitoris, formation or repair of a vagina (vaginoplasty), and repair of the urethra.
Congenital adrenal hyperplasia can be life-threatening because it can cause serious abnormalities of electrolytes (sodium and potassium) in the blood. These are diagnosed with blood tests and treated with corticosteroids.
Last full review/revision April 2006 by Gregory S. Liptak, MD, MPH