The American College of Obstetricians and Gynecologists (ACOG) says an ovarian cyst is a sac or pouch filled with fluid or other tissue that forms on the ovary. A woman can develop one or many cysts which can vary in size. They’re usually harmless and disappear on their own. According to the National Institutes of Health (NIH), they’re more common during childbearing years.
The Mayo Clinic says most ovarian cysts start during the menstrual cycle. Ovaries normally grow cyst-like structures called follicles each month. Follicles produce estrogen and progesterone and release an egg during ovulation. Sometimes a normal monthly follicle just keeps growing. When that happens, it becomes known as a functional cyst.
There are two types of functional cysts says WomensHealth.gov. Follicle cysts form when the follicle sac doesn't break open to release the egg and then keeps growing. Corpus luteum cysts form if the sac doesn't dissolve. Instead, it seals off after the egg is released. Then fluid builds up inside.
Most ovarian cysts don’t cause symptoms. When they do, the Mayo Clinic and NIH list symptoms including fullness or heaviness in the abdomen; constant or intermittent dull ache that may radiate to the lower back and thighs; pain during bowel movements or pressure on the bowels; pain in the pelvis shortly before or after a menstrual period; pain with intercourse; nausea, vomiting or breast tenderness; pressure on the rectum or bladder causing a need to urinate more frequently or difficulty emptying the bladder completely. NIH adds menstrual period changes aren’t common with follicular cysts but are with corpus luteum cysts.
WomensHealth.gov says a common treatment for women in their childbearing years, with no symptoms or having a fluid-filled cyst, is watchful waiting. Patients wait for a second exam after one to three months so the doctor can see if the cyst has changed in size.
NIH says surgery may be needed for complex ovarian cysts that don't disappear, for cysts that cause symptoms, for simple ovarian cysts that are larger than five to ten centimeters, and for women who are menopausal or near menopause.