Ovarian cysts are sacs or pockets in the ovaries that are filled with fluid, reports Mayo Clinic. A lot of women develop ovarian cysts in their lifetime, and most of these cysts are harmless and disappear on their own.
Some ovarian cysts causes symptoms to occur, such as pelvic pain that spreads to the lower back and thighs, that occur just before a woman's period begins or ends or that occur during sexual intercourse, according to Mayo Clinic. Some women experience pain or pressure on the bowels, nausea and vomiting, stomach fullness or heaviness, or bladder pressure that causes frequent urination. A woman should seek medical attention when experiencing pelvic pain that is serious and sudden or accompanied by fever or vomiting.
Functional cysts occur naturally in the ovaries as they go through the menstrual cycle, reports Mayo Clinic. Follicles develop on the ovaries to produce estrogen and progesterone and to release an egg when a woman is ovulating. When one of these follicles continues to grow, a functional cyst forms. One type of functional cyst is the follicular cyst caused when the follicle does not release the egg. Instead, it increases in size and becomes a cyst. The other type is a corpus luteum cyst formed when a ruptured follicle produces an excess amount of progesterone and estrogen.