Disorders of sex development (DSD) are congenital conditions in which development of chromosomal, gonadal or anatomical sex is atypical.  A subset of children have disorders that present at birth with ambiguous genitalia (i.e., a genital phenotype that is neither clearly male nor female). Most causes of this are genetic. One exception is virilization of a 46,XX fetus due to maternal virilizing tumors or maternal exposure to androgenic drugs. This topic addresses the diagnosis and management of patients who are born with a genetic cause of ambiguous genitalia.
Consensus statement on management of intersex disorders 
Sex chromosome DSD: karyotype is not the typical 46,XX or 46,XY.
46,XY DSD: chromosomally male but DSD results from:
A defect in testicular development
A disorder of androgen synthesis or action
Syndromes associated with defects in genital development, including cloacal anomalies, other genetic syndromes, vanishing testis syndrome, and congenital hypogonadotropic hypogonadism.
46,XX DSD: chromosomally female but DSD results from:
Defects in ovarian development
Disorders leading to high levels of androgens; congenital adrenal hyperplasia is by far the most common cause
Abnormalities of the mullerian ducts (dysgenesis or hypoplasia), uterus, or vagina.