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Unless you're hoping to have a child (or just saw a picture of an adorable baby), you probably don't give your ovaries much thought. So it might be a little unsettling to realize that around the time when you're menstruating, there's a good chance that you'll develop an ovarian cyst and never realize it. But before you freak, know this: It's usually harmless.

Still, that doesn't mean that you shouldn't learn more what's going on inside your own body every month. And in some cases, ovarian cysts can cause pelvic pain and more serious complications. Here's everything you should know about this super-common cyst.

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Wait, ovaries and fallopian tubes? Refresh my memory…
Since biology class was a long time ago, here's a quick primer: Inside your pelvis, your uterus is flanked by two ovaries, each one roughly the size of an almond. During your childbearing years, one of your ovaries will swaddle an egg in a fluid-filled space called a follicle, then release the egg into a fallopian tube about once a month. That follicle basically self-combusts afterward and is absorbed into the body.

Right, so how does the cyst form?
Pretty easily, actually.

"Your body basically sets you up to get ovarian cysts," said Dr. Mary Jane Minkin, a clinical professor of obstetrics, gynecology, and reproductive sciences at Yale University School of Medicine .

If the follicle doesn't release the egg, then it can grow bigger and develop into a follicle cyst. Or, you can also develop what's called a corpus luteum cyst, a cavity that forms after the follicle ruptures and releases the egg. These cysts can bleed and cause pain the pelvic area. Usually, these things disappear in under a few weeks and are pretty small (often about 1 to 2 millimeters), but it's possible to have a larger cyst that can measure into the inches, too.

Anything else?
Yes. It's also possible to develop something called a dermoid cyst, which forms when cells in the ovary start dividing, even though they haven't been fertilized. These aren't common, Minkin said, but they can grow larger—even up to 10 centimeters, or almost 4 inches. And since this type of cyst contains the genetic material for a human life, you can find hair and teeth inside them, she says. Dermoid cysts that are large or cause other problems may need to be surgically removed.

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How do I know if I have an ovarian cyst?
Oftentimes, you won't. Many functional ovarian cysts won't trigger any symptoms, and "the vast majority of the time, they go away on their own," Minkin said. And in case you're wondering, follicle cysts don't often cause any changes to your menstrual cycle, though you might experience some bleeding if you have a corpus luteum cyst.

Then how does anyone find out they have a cyst in the first place?
Ovarian cysts can turn up at a routine gyno visit—doctors might find the bigger ones during a pelvic exam (a surprisingly controversial procedure these days) or spot them after a luckily-timed ultrasound. But other women will experience symptoms from their cysts—mainly pain in the pelvic or abdominal areas—and those are the patients that usually wind up in their gyno's office.

"Most of the ovarian cysts I find [in my practice] are from patients who tell me they're experiencing pain," Minkin said.

What other ovarian cyst symptoms I should know about?
There are also more severe symptoms of ovarian cysts, like a fever, nausea, and vomiting. Those are all signs that you may have an infection, and you should get to a doctor ASAP.

But one of the scenarios that worries experts the most, Minkin said, is when the cyst causes an ovary to "twist," which could not only cause an infection, but could cut off the blood supply to the ovary, which can cause permanent damage. It's a problem known as adnexal torsion, and it's just as serious as it sounds. If that occurs—and it's not common—you'll likely feel a sudden pain in your abdomen and may also have some nausea. If this happens, you'll want to let your doctor know about it right away as it's considered a medical emergency.

How does my doctor test me for a cyst?
Oftentimes, your doctor will confirm that you have a cyst after giving you a vaginal ultrasound; the image of the cyst shows up on the scan. But it's also possible that, if you're in pain, your gyno will suspect that you have a cyst based on your symptoms alone.

Either way, your doctor might decide to take a watchful waiting approach, and simply monitor the cyst for a few weeks or month. "We try to avoid operating on someone unless we have to," Minkin said.

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What if I need surgery?
You might need to go under the knife, especially if you're at risk for "twisting," Minkin said. Your doctor might also consider it if the cyst has lingered for longer than three menstrual cycles, it's bigger than 4 inches, or if there's any suspicion that the mass could be a tumor. (More on that later.)

If you do need surgery, you'll likely undergo one of two procedures: a laparoscopy or a laparotomy. Both will require general anesthesia.

Is there any way I can prevent them?
Maybe. If you're not pregnant, then taking birth control pills might help.

"They suppress ovulation," Minkin said, and that might prevent a cyst from forming in the first place.

That said, birth control pills won't help a cyst go away faster, according to a 2014 study from the Cochrane Collaboration. In the past, some doctors recommended BC as a treatment option for ovarian cysts, but the researchers of the 2014 study said that this advice was based on less-than-stellar data and that a better strategy was that of watchful waiting.

What is polycystic ovary syndrome?
About 7 percent of women may have this hormonal disorder, according to a 2004 study in the Journal Clinical Endocrinology & Metabolism. Like its name implies, people with the condition can develop multiple ovarian cysts. They also can have irregular periods, trouble getting pregnant, and symptoms like a deepened voice and increase in body hair (both of which tend to show up when a person has high levels of male hormones). But keep in mind, this is a hormonal syndrome—it's not synonymous with having multiple cysts during your lifetime.

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Can I still get ovarian cysts if I'm past menopause?
Most of the time, cysts develop in pre-menopausal women. But it's still possible to get them as you age, perhaps especially in the earlier post-menopausal years. In fact, one 2010 study in the American Journal of Obstetrics & Gynecology concluded that they might be fairly common. After looking at the transvaginal ultrasound test results of nearly 16,000 women who were older than 55, the researchers found that about 14 percent of the subjects had a cyst at their first screening. About one-third of those cysts disappeared the following year.
The bottom line: Ovarian cysts still make an appearance in women after menopause—and doctors shouldn't automatically assume that all of them are cancerous.

Any chance that an ovarian cyst could be cancerous?
Yes, there's a small chance that a cyst could be ovarian cancer. And like many other cancers, your risk does increase with age, Minkin said. (About half of the women who develop it are older than 63.) Each year, about 21,000 women receive this diagnosis, according to the American Cancer Society. It's also the fifth cause of cancer deaths in women.

If your doctor is trying to determine whether your cyst is cancerous, she'll probably do an ultrasound first. That test won't definitively prove the mass is, in fact, cancer, but it can help your MD determine whether it's filled with fluid (a functional cyst) or whether it's solid (possibly a tumor).

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This article originally appeared on Health.com.