Context: Polycystic ovary syndrome (PCOS) is a very common endocrinopathy with a heterogeneous presentation whose etiology is still uncertain. Not surprisingly, therefore, the definition of, and diagnostic criteria for, PCOS remain controversial.

Objective: The objective of the study was to review and justify the basis for the recently revised definition of PCOS arising from the joint European Society for Human Reproduction & Embryology/American Society for Reproductive Medicine (ESHRE/ASRM) Rotterdam workshop in 2003.

Intervention(s): The Rotterdam criteria take account of the broad spectrum of presenting features of PCOS, including women with hyperandrogenism but regular menses and, more controversially, those with menstrual disturbance without overt androgen excess. POSITIONS: The Rotterdam criteria for definition and diagnosis of PCOS, in the opinion of this author, represent a significant advance in recognizing the broad spectrum of presentation of the syndrome and acknowledge that the clinical and biochemical features may vary with time within individuals. The important refinements when compared to the 1990 NIH definition of PCOS are: 1) inclusion of polycystic ovarian morphology; and 2) inclusion of subjects with hirsutism and regular menses.

Conclusions: These new diagnostic criteria for PCOS reflect the significant advances, particularly from studies of familial PCOS, in understanding of the etiology of the syndrome and the basis for its heterogeneity. Under the revised diagnostic criteria, the inclusion of women with hyperandrogenism and regular cycles has met with general agreement. The inclusion of women with oligomenorrhea and polycystic ovaries who do not have clear evidence of androgen excess is, in the opinion of this author, also justified but remains a contentious issue and one that requires further investigation.