The ovaries are small, almond-shaped organs located in the pelvis, one on each side of the uterus. They are fundamental components of the female reproductive system. Beyond housing and releasing eggs for fertilization, ovaries also produce hormones such as estrogen and progesterone. These hormones regulate the menstrual cycle and support reproductive health.
Normal Ovary Size and Its Variations
The size of an ovary changes throughout a woman’s life, reflecting different stages of development and hormonal activity. During the reproductive years, an adult ovary measures approximately 3 to 5 cm in length, 1.5 to 3 cm in width, and 0.6 to 1.5 cm in thickness, with an average volume ranging from about 6 to 10 cubic centimeters (mL).
Before puberty, ovaries are small, less than 2 cm long, with a volume under 1 cubic centimeter. They increase in size, reaching adult dimensions around puberty. During the reproductive years, ovarian size can fluctuate throughout the menstrual cycle due to developing follicles and corpus luteum formation after ovulation.
During pregnancy, hormonal shifts can lead to a temporary increase in ovarian size. Following menopause, as hormonal production declines and egg reserves are depleted, ovaries shrink. They may measure around 1.5 to 2 cm in length and have a volume as low as 1 to 2 cubic centimeters.
How Ovary Size is Assessed
Healthcare providers use imaging techniques to measure ovarian size. Ultrasound is the primary method for evaluating pelvic organs, including the ovaries. It uses sound waves to create images of internal structures.
Transvaginal ultrasound is preferred for assessing ovarian size due to clearer, more detailed images. A probe is inserted into the vagina for a closer view of the ovaries. This method allows precise measurement of ovarian volume.
Transabdominal ultrasound is an alternative, particularly for younger patients or when a transvaginal approach is not appropriate. A probe is moved across the lower abdomen. While it visualizes the ovaries, images may be less detailed than transvaginal ultrasound, particularly with significant abdominal tissue.
Medical Conditions Influencing Ovary Size
Changes in ovarian size can indicate underlying medical conditions. Enlarged ovaries can be associated with conditions including Polycystic Ovary Syndrome (PCOS). In PCOS, ovaries may appear larger than typical and contain numerous fluid-filled sacs. An ovarian volume greater than 10 cubic centimeters is a common diagnostic criterion for PCOS.
Ovarian cysts can cause enlargement. Functional cysts, such as follicular or corpus luteum cysts, are common and usually resolve, but can temporarily increase ovarian size. Other cysts, like endometriomas associated with endometriosis, or benign tumors such as cystadenomas and dermoid cysts, can enlarge ovaries. Endometriomas over 4 cm may require further evaluation.
Conversely, smaller ovaries can indicate conditions like Primary Ovarian Insufficiency (POI). In POI, ovaries stop functioning normally before age 40, appearing small with fewer developing follicles. Genetic factors, including Turner syndrome, are causes of POI, leading to underdeveloped or degenerating ovaries.