Diagnostic approach to the newborn with ambiguous genitalia.

When assessing an infant with ambiguous genitalia, there are some important points to remember: Do not delay the evaluation of a patient with ambiguous genitalia. A delay may expose the patient unnecessarily to a life-threatening situation, such as a salt-losing crisis associated with 21-hydroxylase deficiency or one of the testosterone biosynthetic defects. Also, it is unfair to expect the family to be able to deal emotionally with the uncertainty of unresolved gender assignment. Never perform a buccal smear. There is absolutely no indication for performing a buccal smear at any point in the evaluation of any patient with ambiguous genitalia. Use of a buccal smear to determine gender assignment was helpful decades ago, before analysis of human chromosomes was possible. With current cytogenetic methodologies that can detect chromosomal mosaicism and subtle abnormalities of the X and Y chromosomes, there is never an indication to perform a buccal smear. Never make a gender assignment on the basis of the appearance of the external genitalia alone. The chromosomal sex and gonadal sex need to be determined first. The parents' feelings regarding the desired sex of the child, gender identity and fertility need to be discussed. Once there are sufficient data, gender assignment can be made. Gender assignment should be made as soon as possible after birth, but absolutely should be made by 18 months of age, when children develop gender identity. Never equivocate in the assignment of gender. The parents and the physicians must be absolutely certain of the gender assignment and must view their decision as final. Follow-up visits with the family ideally include an assessment of their acceptance of the gender assignment of the child. If there is ambivalence, steps must be taken to identify the source of ambivalence and to clarify the issues.