There are two ovaries on each side of the uterus in the ovarian fossa. They are oval in shape and with a mean volume of approx 4.9ml. The ovary often lies on the internal iliac artery and vein but does not maintain a consistent relationship with these vessels.
On the baseline, imaging ovaries are evaluated for normally expected findings and to screen any abnormality.
In the first half of the menstrual cycle (follicular phase) a normal ovary will demonstrate multiple Antral follicles which measures between 2-9 mm in maximum diameter, they are best evaluated on D2 or D3 of the menstrual cycle. Normal AFC is 5-10 in each ovary, if AFC is < 4 combined in both ovaries it is decreased ovarian reserve. If AFC > 12 in any / either ovaries it indicates polycystic ovaries. Normal stromal blood flow velocity is 6-12cm/sec.
In a natural cycle, a dominant follicle of size 17-24mm develops in one of the ovaries matures, and releases the egg (ovum) during ovulation.
On color Doppler, flow velocity tends to increase at and immediately after ovulation.
After ovulation, a corpus luteum is frequently seen during the second half of the menstrual cycle (secretory phase).
On power Doppler, it appears like a ring of fire due to increased blood flow.
The Corpus luteum appears as a round anechoic cystic mass with a homogenous, thick, moderately echogenic wall.
