A very large proportion of young Danish women have polycystic ovaries: is a revision of the Rotterdam criteria needed?

According to the Rotterdam 2003 criteria, an ovary is defined as polycystic if 12 or more follicles of 2-9 mm are present, when evaluating the ovary by ultrasonography on Days 3-5 of the menstrual cycle in women not using hormonal contraceptives. The aim of this population-based study was to estimate the prevalence of polycystic ovaries (PCO) in a representative sample of young Danish women according to the Rotterdam criteria. From a Danish pregnancy cohort established in 1988-1989, 267 (61%) young adult daughters agreed to participate in a clinical examination and 174 (40%) consented to vaginal ultrasound. Sufficient image quality in at least one ovary was obtained from 154 women. Both users and non-users of hormonal contraceptives were included and the examination was not restricted to a particular time of the menstrual cycle. The median (range) age was 20.1 (19.5-21.0) years. The median follicle number per ovary was 14 (6-30) and 12 or more follicles were counted in 104 of the 154 women. Thus, the prevalence was estimated to 68% [95% confidence interval (CI): 60-74%]. PCO were present in 80% (95% CI: 65-89%) of non-users (n = 44) of hormonal contraceptives. Of the 104 women with PCO, 41% (95% CI: 32-51%) could be defined as having polycystic ovary syndrome. A very large proportion of the young women had PCO according to the Rotterdam 2003 criteria. As the number of follicles is higher at a younger age, we believe the Rotterdam criteria should be revised, particularly to avoid misdiagnosis in this age group.