Every female reproductive system has an ovary on each side of her body. Each ovary produces an ovum that, when released, travels down the fallopian tube into the uterus and becomes fertilised by a sperm.
An ovarian cyst is a fluid-filled sac formed in the ovary. It usually forms during ovulation. Ovulation transpires when the woman’s ovary releases an egg each month. Many women don't have ovarian cyst symptoms. The cysts are usually harmless.
Functional cyst
A functional ovarian cyst is a sac that holds a maturing egg. It forms on the surface of a woman's ovary during or after ovulation and goes away after the egg is released. Yet if the ovary does not release an egg, or if the sac closes up after the egg is released, the sac can swell up with fluid.
Functional ovarian cysts are not the same as ovarian growths caused by other problems, such as cancer. Most of these cysts are harmless, without symptoms, and they go away without treatment. But if a cyst becomes large, it can twist, rupture, or bleed. A ruptured ovarian cyst can be very painful.
There are 2 types of functional cysts:
- Follicular cyst
Around the midpoint of a woman’s menstrual cycle, an egg bursts out of its sac or follicle and travels down the fallopian tube. Follicular cyst occurs when the follicle does not release an egg, and that sac swells up with fluid.
- Corpus luteum cyst or luteal cyst
This occurs when the sac releases an egg and then reseals and fills with fluid.
What types of cysts are harmful?
As functional cysts rarely cause pain or harm and often disappear on their own within 2 – 3 menstrual cycles, there are other types of cysts that are not related to the normal function of a woman’s menstrual cycle. Some ovarian cysts become large, which can also make them rupture. Some examples are:
- Dermoid cyst
Also called teratoma, dermoid cyst can contain tissue, such as hair, skin, or teeth because it forms from embryonic cells. It is rarely cancerous but can become large and cause the ovary to move out of position, which increases the chance of ovarian torsion or the painful twisting of the ovary. Ovarian torsion may result, too, in decreasing or stopping blood flow to the ovary.
- Cystadenoma
This cyst develops on the surface of an ovary and might be filled with a watery or a mucous material. Like a dermoid cyst, cystadenoma may also grow large and cause the ovary to move out of position, causing ovarian torsion.
- Endometrioma
Also known as a chocolate cyst, this cyst develops when uterine endometrial cells grow outside a woman’s uterus or what is called endometriosis. Some of the tissues can attach to the ovary and form a growth.