Ovarian cysts are fluid-filled sacs that form on or in the ovary. They are very common in women of reproductive age. Ovarian cysts typically do not produce symptoms or signs unless the cyst is very large, so it is common to have an ovarian cyst and have no symptoms or signs. Rupture of a cyst, bleeding into a cyst, rapid growth, and twisting of the cyst around its blood supply (torsion) can all cause abdominal or pelvic pain.
Causes of ovarian cysts
The most common cause of ovarian cysts is hormonal fluctuations or imbalances. Cysts may form during the normal menstrual cycle (follicle or follicular cysts). Corpus luteum cysts can be found after ovulation and in early pregnancy. Other causes of ovarian cysts include endometriosis, infections, polycystic ovarian syndrome, benign tumors, and rarely, cancers.
United States. Department of Health & Human Services. Office on Women's Health. "Ovarian Cysts." May 22, 2018. <https://www.womenshealth.gov/a-z-topics/ovarian-cysts>.