Ovarian volume and follicle number in the diagnosis of polycystic ovary syndrome in Chinese women.

Objective: To assess the value of ovarian volume and follicle number in the diagnosis of polycystic ovary syndrome (PCOS) in a Chinese population.

Methods: This study included 432 women with PCOS selected using the National Institutes of Health criteria, who were compared with 153 age-matched women as controls. All participants were given a transvaginal or transrectal ultrasound scan during day 3-5 of the menstrual cycle (for regularly menstruating women) or randomly (for oligomenorrheic or amenorrheic women). The ovarian volume (calculated using the simplified formula: 0.5 x length x height x width) and follicle number were obtained and the best diagnostic cut-off values were evaluated using receiver-operating characteristics (ROC)-curve analysis.

Results: The 10(th) and 90(th) centiles of ovarian volume in PCOS patients were 4.89 and 15.79 cm(3), respectively, and the median was 9.21 cm(3); the 10(th) and 90(th) centiles of follicle number were 8 and 19, respectively, and the median was 12. The 10(th) and 90(th) centiles of ovarian volume in controls were 2.43 and 7.75 cm(3), respectively, and the median was 4.46 cm(3); the 10(th) and 90(th) centiles of follicle number were 3 and 10, respectively, and the median was 6. The differences in ovarian volume and follicle number between patients and controls were statistically significant. The areas under the ROC curves for mean ovarian volume (MOV), maximum ovarian volume (MaxOV), mean follicle number (MFN) and maximum follicle number (MaxFN) to diagnose PCOS were 0.898, 0.882, 0.909 and 0.911, respectively. Setting the threshold for MOV at 6.4 cm(3) (sensitivity 81%, specificity 85.6%), the threshold for MaxOV at 7.9 cm(3) (sensitivity 78%, specificity 85.6%), the threshold for MFN at 10 (sensitivity 85.2%, specificity 88.8%) and the threshold for MaxFN at 12 (sensitivity 85.2%, specificity 92.6%) obtained the best compromise between sensitivity and specificity, based on the Youden index.

Conclusions: We conclude that ovarian volume and follicle number have satisfactory power for use in the diagnosis of PCOS. Cut-offs of 6.4 cm(3), 7.9 cm(3), 10 and 12, for MOV, MaxOV, MFN and MaxFN, respectively, obtained the best compromise between sensitivity and specificity for the diagnosis of PCOS in Chinese women.