Background: This study revisited the ovarian volume (OV) as a diagnostic criterion for polycystic ovaries (PCO). Indeed, a threshold of 10 cm(3) for the OV, chosen at the polycystic ovary syndrome (PCOS) international consensus held at Rotterdam in 2003, was to date not based on appropriate studies such as receiver operator characteristic (ROC) curve analysis.
Methods: This prospective study included 154 women with PCOS, selected by using the former National Institutes of Health criteria, who were compared with 57 women with normal ovarian function. Ultrasound examination was performed between cycle days 2 and 7 with a 7 MHz transvaginal transducer.
Results: Mean OV, ovarian area (OA) and follicle number (FN) values were significantly higher in the PCOS group than in controls. The area under the ROC curve (AUC) was >0.9 for all three criteria, indicating a satisfactory diagnostic potency for each. Concerning the OV, setting the threshold at 7 cm(3) offered the best compromise between specificity (91.2%) and sensitivity (67.5%). In comparison, specificity and sensitivity were 98.2 and 45%, respectively, with a threshold at 10 cm(3). Nevertheless, the highest AUC was obtained for FN (0.956) and then for OA (0.941).
Conclusions: OV is a good diagnostic criterion for PCO but, on the basis of the present data, we propose to lower its threshold to 7 cm(3). The FN >12 still appears as the best diagnostic criterion. The OA could be used as a surrogate for OV in difficult situations.