Updated ultrasound criteria for polycystic ovary syndrome: reliable thresholds for elevated follicle population and ovarian volume
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STUDY QUESTION: Do the ultrasonographic criteria for polycystic ovaries supported by the 2003 Rotterdam consensus adequately discriminate between the normal and polycystic ovary syndrome (PCOS) condition in light of recent advancements in imaging technology and reliable methods for estimating follicle populations in PCOS? STUDY ANSWER: Using newer ultrasound technology and a reliable grid system approach to count follicles, we concluded that a substantially higher threshold of follicle counts throughout the entire ovary (FNPO)-26 versus 12 follicles-is required to distinguish among women with PCOS and healthy women from the general population. WHAT IS KNOWN ALREADY: The Rotterdam consensus defined the polycystic ovary as having 12 or more follicles, measuring between 2 and 9 mm (FNPO), and/or an ovarian volume (OV) >10 cm(3). Since their initial proposal in 2003, a heightened prevalence of polycystic ovaries has been described in healthy women with regular menstrual cycles, which has questioned the accuracy of these criteria and marginalized the specificity of polycystic ovaries as a diagnostic criterion for PCOS. STUDY DESIGN, SIZE, DURATION: A diagnostic test study was performed using cross-sectional data, collected from 2006 to 2011, from 168 women prospectively evaluated by transvaginal ultrasonography. Receiver operating characteristic (ROC) curve analyses were performed to determine the appropriate diagnostic thresholds for: (i) FNPO, (ii) follicle counts in a single cross section (FNPS) and (iii) OV. The levels of intra- and inter-observer reliability when five observers used the proposed criteria on 100 ultrasound cases were also determined. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ninety-eight women diagnosed with PCOS by the National Institutes of Health criteria as having both oligo-amenorrhea and hyperandrogenism and 70 healthy female volunteers recruited from the general population. Participants were evaluated by transvaginal ultrasonography at the Royal University Hospital within the Department of Obstetrics, Gynecology and Reproductive Sciences, University of Saskatchewan (Saskatoon, SK, Canada) and in the Division of Nutritional Sciences' Human Metabolic Research Unit, Cornell University (Ithaca, NY, USA). MAIN RESULTS: Diagnostic potential for PCOS was highest for FNPO (0.969), followed by FNPS (0.880) and OV (0.873) as judged by the area under the ROC curve. An FNPO threshold of 26 follicles had the best compromise between sensitivity (85%) and specificity (94%) when discriminating between controls and PCOS. Similarly, an FNPS threshold of nine follicles had a 69% sensitivity and 90% specificity, and an OV of 10 cm(3) had a 81% sensitivity and 84% specificity. Levels of intra-observer reliability were 0.81, 0.80 and 0.86 when assessing FNPO, FNPS and OV, respectively. Inter-observer reliability was 0.71, 0.72 and 0.82, respectively. LIMITATIONS, REASONS FOR CAUTION: Thresholds proposed by this study should be limited to use in women aged between 18 and 35 years. WIDER IMPLICATIONS OF THE FINDINGS: Polycystic ovarian morphology has excellent diagnostic potential for detecting PCOS. FNPO have better diagnostic potential and yield greater diagnostic confidence compared with assessments of FNPS or OV. Whenever possible, images throughout the entire ovary should be collected for the ultrasonographic evaluation of PCOS. STUDY FUNDING AND COMPETING INTEREST: This study was funded by Cornell University and fellowship awards from the Saskatchewan Health Research Foundation and Canadian Institutes of Health Research. The authors have no conflict of interests to disclose.