Ovarian cysts are fluid-filled sacs that grow inside or on top of one (or both) ovaries. A cyst is a general term used to describe a fluid-filled structure. Ovarian cysts are usually asymptomatic, but pain in the abdomen or pelvis is common.
What Are the Ovaries? What Do the Ovaries Do?
The ovaries are reproductive organs in women that are located in the pelvis. One ovary is on each side of the uterus, and each is about the side of a walnut. The ovaries produce eggs and the female hormones, estrogen and progesterone. The ovaries are the main source of female hormones that control sexual development including breasts, body shape, and body hair. The ovaries also regulate the menstrual cycle and pregnancy.
What Is Ovulation?
Ovulation is controlled by a series of hormone chain reactions originating from the brain’s hypothalamus. Every month, as part of a woman’s menstrual cycle, follicles rupture, releasing an egg from the ovary. A follicle is a small fluid sac that contains the female gametes (eggs) inside the ovary. This process of releasing and egg from the ovary an into the Fallopian tube is known as ‘ovulation’.
What Causes Ovarian Cysts?
Sometimes a follicle does not release an egg during ovulation, and instead it continues to fill with fluid inside the ovary. This is called a ‘follicular cyst’. In other cases, the follicle releases the egg but the sac seals up again and swells with fluid or blood instead of dissolving. This is known as a ‘corpus luteum cyst’. Both of these conditions are types of functional ovarian cysts. Functional ovarian cysts are the most common type of ovarian cysts.
Ovarian Cyst Risk Factors
The following are potential risk factors for developing ovarian cysts:
History of previous ovarian cysts
Irregular menstrual cycles
Infertility
Polycystic ovarian syndrome
Endometriosis
Obesity
Early menstruation (11 years or younger)
Hyperthyroidism
Tamoxifen therapy for breast cancer
