Ambiguous genitalia are genitals that do not look clearly male or clearly female. Instead, they may appear to have characteristics of both female and male genitalia or may be developed incompletely at birth. This is what is often referred to when the term “intersex” or DSD (disorder of sex development) is used. A baby with XX (female-pattern) chromosomes may be born with what looks like a complete penis but an empty scrotum. This is the extreme presentation of congenital adrenal hyperplasia (CAH). A baby with XY (male-pattern) chromosomes may be born with what looks like normal female genitals but a shallow or “blind” vagina that does not lead to a uterus. This is the presentation of complete androgen insensitivity syndrome. Another form of androgen insensitivity syndrome called partial androgen insensitivity syndrome can have an array of genital differences, all along the spectrum between male and female. Incomplete CAH can lead to a variety of partially masculinized genitals, also all along the spectrum.

Some boys with hypospadias have ambiguous genitalia, especially when the hypospadias is severe and the testes are undescended. However, most baby boys with hypospadias do not have any genital ambiguity.