ABSTRACT
With all imaging systems, the ovarian size (i.e. volume) together with the number of preantral follicles are the key and consistent features of polycystic ovaries. Pache and colleagues performed a series of studies to distinguish between normal and polycystic ovaries and to determine the key features of the polycystic ovary4,28,37. First PCOS was defined (on the basis of elevated testosterone or LH) and transvaginal ultrasound (5 MHz) was used to compare those with the syndrome to a control group37. Women with amenorrhea had similar ultrasound features to those with oligomenorrhea. Control ovaries never had a volume of more than 8.0 cm3 or more than 11 follicles. The mean number of follicles was 10 in polycystic ovaries and 5 in normal ovaries. Median values for mean ovarian volume were 5.9 cm3 in controls and 9.8 cm3 in PCOS (p < 0.001); mean follicular size and number were 5.1 vs. 3.8 and 5.0 vs. 9.8 for controls and PCOS, respectively. Stromal echogenicity was also significantly increased in the PCOS patients, based on a semi-quantitative assessment37. The greatest power of discrimination between normal and polycystic ovaries was provided by a combined measurement of follicular size and ovarian volume (sensitivity 92%, specificity 97%).
