A functional ovarian cyst is a sac that forms on the surface of a woman's ovary during or after ovulation. It holds a maturing egg. Usually the sac goes away after the egg is released. If an egg is not released, or if the sac closes up after the egg is released, the sac can swell up with fluid.
Functional ovarian cysts are different from ovarian growths caused by other problems, such as cancer. Most of these cysts are harmless. They do not cause symptoms, and they go away without treatment. But if a cyst becomes large, it can twist, rupture, or bleed and can be very painful.
A functional ovarian cyst forms because of slight changes in the way the ovary makes or releases an egg. There are two types of these cysts:
- A follicular cyst occurs when a sac on the ovary does not release an egg, and the sac swells up with fluid.
- A luteal cyst occurs when the sac releases an egg and then reseals and fills with fluid.
Most functional ovarian cysts do not cause symptoms. The larger the cyst is, the more likely it is to cause symptoms. Symptoms can include:
- Pain or aching in your lower belly, usually when you are in the middle of your menstrual cycle.
- A delay in the start of your menstrual period.
- Vaginal bleeding when you are not having your period.
Some functional ovarian cysts can twist or break open (rupture) and bleed. Symptoms include:
If you have these symptoms, call your doctor right away. Some ruptured cysts bleed enough that treatment is needed to prevent heavy blood loss.
Your doctor may find an ovarian cyst during a routine pelvic exam. He or she may then use a pelvic ultrasound to make sure that the cyst is filled with fluid.
If you see your doctor for pelvic pain or bleeding, you'll be checked for problems that may be causing your symptoms. Your doctor will ask you about your symptoms and menstrual periods. He or she will do a pelvic exam and may do a pelvic ultrasound.