[A neonate with ambiguous genitalia].

In a neonate with ambiguous genitalia, physical examination revealed a phallus. Ultrasonography showed a vagina and uterus, but no gonads. Because of severe undervirilisation in the presence of a uterus, probably due to 46,XY gonadal dysgenesis, parents were advised female sex assignment. When after a few weeks the phallus had increased in size, abdominal laparoscopy showed an underdeveloped uterus. Gonadal biopsy confirmed gonadal dysgenesis. Sex assignment was reconsidered and changed into the male gender.