What are ambiguous genitalia?
At conception, a fetus's gender is already determined based on the 23rd pair chromosome it inherited from the parents. Females have two X chromosomes and males have an X and a Y chromosome. Even though the gender is set, the fetal tissue that will eventually become the female ovaries or male testes (gonads) has not yet begun to take its form. If the hormonal process that causes that tissue to become male or female is disrupted over the following weeks, ambiguous genitalia can develop.
Your obstetric team will most likely be the first ones who notice the ambiguous genitalia. They may see the following:
Characteristics of ambiguous genitalia in genetic females include:
- an enlarged clitoris, or what appears to be a small penis
- a concealed vagina
Characteristics of ambiguous genitalia in genetic males include:
hypospadias, the condition in which the narrow tube that carries urine and semen (urethra) doesn't fully come to the tip of the penis
an abnormally small penis with the urethral opening nearer to the scrotum
no recognizable male genitalia in the most severe cases
the absence of both testicles in what appears to be the scrotum
What causes ambiguous genitalia?
The sexual organs of males and females develop from the same fetal tissue. The same tissue that becomes a penis in a male becomes a clitoris in a female. The main factor controlling the next step is male hormones. The presence of male sex hormones causes male organs to develop and the absence of male hormones causes female organs to develop.
Without enough male hormones, a genetic male will develop ambiguous genitalia. Likewise, a genetic female will develop ambiguous genitalia if male hormone is present.
Possible causes of ambiguous genitalia in genetic females:
- Congenital adrenal hyperplasia (CAH)
Certain forms of this genetic condition cause the adrenal glands to make excess male hormones (androgens).
Congenital adrenal hyperplasia is the most common cause of ambiguous genitalia in newborn females. Males aren't born with ambiguous genitalia, but they may have unusually fast development and virility problems.
CAH is present in about one in 15,000 newborns.
Another type of CAH, called "salt-losing," is a potentially life-threatening enzyme deficiency. Male and females are equally affected. Treatment is available if diagnosed early.
In some cases, if the fetus is female, the mother of a fetus with CAH can be given medications during pregnancy to lessen the effects of the enzyme deficiency.
CAH is a recessive gene, meaning that each parent carries one copy of the gene and transmits the gene at the same time to the child. Carrier parents have a 25 percent chance with each pregnancy of having an affected child.
- The mother's ingestion of a substance with male hormone activity
- for example, progesterone (taken in the early stages of pregnancy to stop bleeding)
- Tumors in the fetus or the mother that produce male hormones
Possible causes of ambiguous genitalia in genetic males:
- impaired testicle development caused by genetic abnormalities or unknown causes
- Leydig cell aplasia, a condition that impairs testosterone production
- Androgen insensitivity syndrome
5alpha-reductase deficiency, an enzyme deficiency that impairs normal male hormone production
The mother's ingestion of substances with female hormone activity
for example, estrogens, or anti-androgens. This is unusual, but could occur if a woman taking birth control pills gets pregnant despite taking the pills. Then, not knowing she's pregnant, she continues taking the pills into pregnancy for several weeks. Also some "nutritional supplements" contain plant estrogens.
What is the long-term outlook for a child with ambiguous genitalia?
Some children born with ambiguous genitalia have normal internal sexual organs that allow them to live a fertile reproductive life. Others may be infertile or experience difficulty conceiving a child. Sometimes there is an increased risk of tumors in the gonads later in life.