Ovary in Anovulatory Cycles

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.