Ovarian cysts are fluid-filled sacs or pockets within or on the surface of an ovary. Women have two ovaries — each about the size and shape of an almond — located on each side of the uterus. Eggs (ova) develop and mature in the ovaries and are released in monthly cycles during your childbearing years. Many women have ovarian cysts at some point of time. Most ovarian cysts present little or no discomfort and are harmless. The majority of ovarian cysts disappear without treatment within a few months. However, ovarian cysts especially those that have ruptured sometimes produce serious symptoms.
Your ovaries normally grow cyst-like structures called follicles each month. Follicles produce the hormones estrogen and progesterone and release an egg when you ovulate. Sometimes a normal monthly follicle keeps growing. When that happens, it is known as a functional cyst.
There are two types of functional cysts:
Follicular cyst.Around the midpoint of your menstrual cycle, an egg bursts out of its follicle and travels down the fallopian tube in search of sperm and fertilization. A follicular cyst begins when something goes wrong and the follicle doesn’t rupture or release its egg. Instead, it grows and turns into a cyst.
Corpus luteum cyst.When a follicle releases its egg, the ruptured follicle begins producing large quantities of estrogen and progesterone for conception. This follicle is now called the corpus luteum. Sometimes, however, the escape opening of the egg seals off and fluid accumulates inside the follicle, causing the corpus luteum to expand into a cyst. The fertility drug clomiphene (Clomid, Serophene), which is used to induce ovulation, increases the risk of ovarian cyst. Functional cysts are usually harmless, rarely cause pain, and often disappear on their own within two or three menstrual cycles.