The size of the ovaries may be an important indicator of pathology. During the reproductive years, mean size is 8 mL (standard deviation [SD], 2–3 mL; range, 5–15 mL). Post-menopausal ovaries are small, with a mean size of 3.6 mL (SD, 1.4 mL; range, 1–14 mL).
FIGURE 3 How to spot the ovaries
(A) Anechoic follicles are markers of the ovary during the reproductive years. (B) The ovaries in relation to the hypogastric vessels. (C) Gray-scale image of the corpus luteum and the same image in (D) color Doppler.
A word about terminology: Don’t call follicles “cysts”
During a normal menstrual cycle, one or more follicles mature, reaching about 2 to 2.5 cm in diameter around mid-cycle. Do not call these follicles “cysts” or “follicular cysts.” They are follicles. Calling them cysts, or even including the word cyst in their description, suggests to many gynecology and radiology providers—and to patients themselves—the idea of pathology.1
An exception to that rule: An ovary that is larger than 12 to 14 mL and has a hyperechoic hilus and more than 12 small (4–5 mm), peripherally pushed follicles is usually called “polycystic” (FIGURE 4).3 However, not every ovary that fulfills these sonographic criteria is indeed polycystic. At times normal ovaries may contain multiple follicles without any of the clinical or laboratory indications of a polycystic ovary. In these cases, the ovary may be of normal size and may lack a hyperechoic hilus with rich hilar vascularity. We term such ovaries “multicystic” in their appearance.
FIGURE 4 The polycystic ovary
(A) Gray-scale image of a polycystic ovary. The typical hyperechoic hilus is evident (H). (B) Gross pathologic section of a polycystic ovary. (C) 3D orthogonal planes of a large ovary with a multitude of small follicles pushed peripherally by a voluminous hyperechoic hilus. (D) 3D inversion rendering of the same ovary.
We employ 3D inversion rendering to better see and count the number of follicles (FIGURE 4D).
An ovary can have a polycystic appearance in the following clinical situations:
- hyperthyroid state (36% of affected women)
- hyperprolactinemia (50%)
- hypothalamic hypogonadism (24%).
It also can appear polycystic for no apparent reason.
Stay tuned!
Next month, we continue our focus on adnexal imaging by describing (and showing) nonneoplastic ovarian masses.
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