Many people believe that the management of children born with disorders of sexual differentiation is the major management problem in paediatric gynaecology. In fact, it forms only a small part of the practice of a paediatric gynaecologist, occurring in about one in 4500 births. The paediatric gynaecologist is but one member of the multidisciplinary team involved in the care of such children and their parents that includes a paediatric endocrinologist, neonatologist, paediatric surgeon, paediatric urologist, clinical geneticist, clinical psychologist and, if available, social work, nursing and medical ethicist.

The first question asked by parents following delivery of their child is ‘What sex is it?’ Not to be able to answer that question is extremely distressing for all concerned and requires sensitive and informed care. Initial management should include giving the parents as full an explanation as possible but they should be warned that it may take some time before a complete answer can be given, although the information required to assign the sex of rearing is usually available within 48–72 hours.

Embryological development

A degree of knowledge of the development of the internal and external genitalia is required to understand the clinical appearance of the child at birth. Chromosomal sex is determined at fertilisation and depends on whether the ovum is fertilised by a sperm bearing an X or a Y chromosome. Until about 6–7 weeks of gestation, the embryo develops in the same manner, irrespective of gender, and both sexes have both wolffian and müllerian ducts.