Anatomic gynecologic anomalies, including congenital absence of the vagina, defects in lateral and vertical fusion of the mullerian ducts, and disorders of sexual development, occur with surprising frequency in referral practices of reproductive endocrinology and reproductive surgery. This article serves to review the embryology and development of the reproductive system and to describe common genital tract anomalies. Details of surgical or nonsurgical correction of these anomalies are presented. Obstetrical and gynecologic consequences of these defects are described. The reproductive organs consist of gonads, a ductal system, and external genitalia. Although the final maturation of the reproductive organs occurs after birth, the critical developmental steps occur during the embryonic and fetal periods of development. Initially, the reproductive system is capable of developing either along male or female lines independent of whether an XX or XY chromosome complement is present. Sexual differentiation is dependent on the genetic sex, which is determined at fertilization by the presence or absence of the Y chromosome. In the presence of the Y chromosome the gonads develop as testes, leading to the production of hormones that promote the development of the male or wolffian ductal system and the regression of the female or mullerian ductal system. Therefore, sexual differentiation is dependent on the genetic sex, the gonadal sex, and the phenotypic sex. Congenital genital tract anomalies include defects in gonadal and ductal development and defects in external genitalia differentiation. The American Society of Reproductive Medicine published a classification of mullerian anomalies that grouped anomalies in categories based on similarities in clinical presentation, obstetrical outcome, and treatment options. The classification system, however, does not include vaginal anomalies. Therefore, an alternative classification system has been described that separates uterovaginal anomalies into three separate groups on the basis of similar embryonic developmental defects and clinical presentation. The three groups include patients,vith agenesis of the uterus and vagina, patients with defects in vertical fusion (obstructive or nonobstructive), and patients with defects in lateral fusion (obstructive or nonobstructive). One of the greatest responsibilities of the obstetrician is the assignment of a sex to the newborn. A profound dilemma exists in the event of ambiguity of the external genitalia. Ambiguous external genitalia in a newborn is a true medical emergency and represents a diagnostic challenge. The development of ambiguous external genitalia is a result of abnormal or inappropriate androgen representation in utero. A classification scheme for the evaluation of newborns with sexual ambiguity is included in this article. Problems that arise in the external genitalia that are associated with excess virilization of the female fetus or undervirilization of the male fetus are considered intersex states, and the sex of rearing needs to be determined. This section will consider female intersex induced by congenital-adrenal hyperplasia, endogenous and exogenous androgen production, incomplete androgen insensitivity, and 5-alpha reductase deficiency. Successful management of congenital anomalies of the genital tract demands both intense psychologic support and a high degree of surgical skill. In-depth consultation should be obtained or the patients should be referred to centers where such expertise exists and where long-term follow-up can be provided. Certain rules can be applied to each of the categories of congenital genital tract anomalies, but one of the most important rules is that there are no rules, and each case has to be dealt with individually, depending on the patients anatomy, desires, and age.
