Ovarian endometriomas, or “chocolate cysts,” are cysts filled with menstrual blood. They are a sign of endometriosis, a condition that happens endometrial-like tissue travels outside of your uterus. These cysts can cause unpleasant symptoms that your provider can help you manage. In some cases, removing them is the best option.
An ovarian endometrioma is a cyst that’s filled with the same fluid that’s in the lining of your uterus (endometrium). Sometimes called “chocolate cysts,” the fluid inside an ovarian endometrioma resembles chocolate syrup. Instead of being in your uterus, though, ovarian endometriomas form in your ovaries. Having an ovarian endometrioma is a sign that you have endometriosis, a condition that happens when endometrial-like tissue take hold in places outside your uterus.
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Anyone who menstruates can get endometriosis. And only people with endometriosis get ovarian endometriomas. You’re more likely to have endometriosis if you’re between ages 25 and 40. The American Society for Reproductive Medicine (ASRM) has identified four different stages of endometriosis. What stage you’re in depends on how much endometrial-like tissue is outside your uterus, its characteristics, and how deeply it’s embedded in the organ where it’s found, like an ovary. If you have an ovarian endometrioma, you’re in Stage 3 or 4.
About 10% of people who menstruate have endometriosis, and about 17 to 44% of those with endometriosis are estimated to have ovarian endometriomas.
Having an ovarian endometrioma means that you’re more likely to experience unpleasant symptoms related to endometriosis. Ovarian endometriomas:
Ovarian cancer is rare among people with ovarian endometriomas, but these cysts can become cancerous. You and your provider can monitor your cysts and discuss treatment options if there’s concern that an ovarian endometrioma could become cancerous.
Doctors don’t know for sure what causes endometriosis or ovarian endometriomas. The most common theory is that endometriosis happens because some of the endometrial-like tissue that you shed when you menstruate flows backward (retrograde menstruation). Instead of leaving your body through your vagina, some of the tissue travels back through your fallopian tubes and into your ovaries. Each menstrual cycle when your body releases the hormones that make your uterus lining bleed, the out-of-place tissue bleeds, too. It becomes inflamed. Over time, the menstrual blood and the inflamed tissue around it can become an ovarian endometrioma.
Pain or tenderness in your pelvis is the most common way to know that you have an ovarian endometrioma. You may notice other symptoms, too:
Your provider can diagnose an ovarian endometrioma by removing the cyst and examining its cells. Usually, this happens during a laparoscopy. During this procedure, your doctor makes tiny cuts in your abdomen and inserts a thin tube called a laparoscope. Using this tube, your provider can see the cyst, remove a sample of it for testing (biopsy), or remove it entirely. If it’s an ovarian endometrioma, your provider will see both endometrial glands and stroma cells in the sample. With laparoscopy, diagnosis and treatment can happen at the same time.
Physical exams and imaging procedures can provide clues that you have an ovarian endometrioma. If the cyst is especially large, your provider may notice it during a pelvic exam. Transvaginal ultrasounds, magnetic resonance imaging (MRIs), and computed topography scans (CT scans) can let your provider know that you have a mass.
Neither an exam nor imaging provides enough information for your provider to know that the mass is an ovarian endometrioma, though. For example, an ovarian endometrioma and a hemorrhagic cyst often look alike on imaging tests because they both contain blood. To be sure it’s an ovarian endometrioma, your provider must test the tissue.
Test results can’t show for sure whether your cyst is an ovarian endometrioma. But, tests can help your provider rule out other conditions that cause symptoms similar to ovarian endometriomas. Certain tests can also help your provider get closer to a diagnosis. Your provider may order:
There isn’t a cure for ovarian endometriomas, but your provider can remove them if they cause unpleasant symptoms or pose risks to your health.
The best treatment for you depends on lots of factors, like your age, your risk for cancer, your plans for becoming pregnant, including whether or not you’re thinking of in vitro fertilization (IVF). Your provider can recommend the best treatment options based on your unique situation.
Since there’s no cure for endometriosis, there’s no way to stop an ovarian endometrioma from forming. But, your provider may suggest medications to help prevent an ovarian endometrioma from growing bigger or growing back once it’s been removed. Medication can help with managing the pain, too. Your doctor may prescribe:
Your provider can suggest the best options available to you based on whether or not you’re trying to become pregnant.
More research is needed to understand how laparoscopy affects fertility in couples who are trying to become pregnant through IVF. Some research suggests that this procedure can reduce the amount of eggs the ovary makes that are capable of being fertilized (ovarian reserve). This can make it harder to become pregnant. If your ovarian endometriomas are making it hard for your provider to access and collect your eggs, it may be a good idea to remove the ovarian endometriomas regardless.
Weigh the pros and cons of removing your ovarian endometriomas with your provider to decide the best plan for your family planning goals and your health.
There’s no way to prevent endometriosis or endometriomas.
Having ovarian endometriomas means that you have more advanced endometriosis. You should work with your provider to manage any symptoms you’re experiencing with this condition. You may need help with pain management and fertility issues if you’re trying to become pregnant. Even if you’ve had an ovarian endometrioma removed, it’s a good idea to monitor for others. Around 25% of women who have had an ovarian endometrioma removed have had them come back.
The good news is that many of these symptoms ease up around menopause, when your body is no longer responding to the hormone changes that come with menstruation.
You and your provider should check on any suspected ovarian endometriomas. If they’re growing or if they’ve gotten bigger than 4 centimeters, the chances increase that they could become cancerous. Also, it’s a good idea to see your provider if you’re experiencing pain. Your provider can talk you through your options.
You should seek emergency care if you have an ovarian endometrioma that bursts. Pay attention to these warning signs:
A note from Cleveland Clinic
Ovarian endometriomas can cause unpleasant symptoms that can interfere with your life. Knowing that these symptoms usually get better after menopause isn’t comforting if you’re in your reproductive years. If you have an ovarian endometrioma, talk to your provider about treatment options. Your provider can recommend ways to relieve your symptoms based on your health and lifestyle.
Last reviewed by a Cleveland Clinic medical professional on 11/02/2021.
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