In an anovulatory cycle , ultrasound imaging of the ovaries will reveal either a lack of any follicular development , particularly in the hypogonadotropic hypogonadal patient with type I or a few non ovulatory (less than 11mm) follicles . A dominant follicle larger than 16mm in diameter will not develop . A cyst may also be associated with anovulation. Anovulation with PCOD will often have enlarged ovaries greater than 8 cm3 in volume with multiple small subcapsular follicles less than 10mm in diameter . Normal sized ovaries do not rule out PCOD. Anovulation can be diagnosed when serial scans do not show development of a follicle . A mature corpus luteum is noted sonographically in about 50% of patients after ovulation . If pregnancy does not occur the corpus luteum generally degenerates and disappears just before menstruation . Corpus luteum cysts may be 4 to 6 cm in diameter and occasionally even large but are more commonly 2.5 to 3 cm in diameter . They may persist for 4 to 12 weeks and may be responsible for suppressing normal follicular development until they resolve .
In PCOD the ovaries are increased in size . The mean volume of the ovary is 12.5 cm3 with a range from 6 to 30 cm. The classical anatomic criteria are not present in all patients with clinical or endocrine findings suggestive of PCOD . An ultrasound showing ovarian enlargement can help make the diagnosis , but a normal ultrasound examination with normal size ovaries does not rule out PCOD if the clinical or biochemical abnormalities characteristic of the syndrome are present . Ultrasound may also suggest the diagnosis of PCOD in a patient with normal sized ovaries and the clinical and or endocrine criteria of PCOD by confirming anovulation :
-Enlarged ovary (volume more than 8cm3) ;
-Multiple small cysts ( 0.2-0.6 cm) ;
-Anovulation (lack of follicular development ) ;
-Resting or follicular phase endometrium .