Ovarian Endometrioma

Ovarian endometriomas, or “chocolate cysts,” are cysts filled with menstrual blood. They are a sign of endometriosis, a condition that happens when 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.


What is an ovarian endometrioma?

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 takes hold in places outside your uterus.


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Who does it affect?

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.

  • Stage 1: You have a small amount of tissue, mostly surface-level on the organ where it’s found.
  • Stage 2: You have more tissue than in Stage 1, and some of it is embedded.
  • Stage 3: You have a lot of tissue that’s deeply embedded, including small endometriomas.
  • Stage 4: You have a lot of tissue that’s deeply embedded, including large endometriomas.

How common are ovarian endometriomas?

About 10% of people who menstruate have endometriosis, and about 17 to 44% of those with endometriosis are estimated to have ovarian endometriomas.


How do ovarian endometriomas affect my body?

Having an ovarian endometrioma means that you’re more likely to experience unpleasant symptoms related to endometriosis. Ovarian endometriomas:

  • May cause you to feel pain in your pelvis.
  • May increase your risk of getting ovarian cancer.
  • May make it harder for you to become pregnant.

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.

Symptoms and Causes

What causes an ovarian endometrioma?

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.


What are the symptoms?

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:

  • Periods that are especially painful.
  • Pain during intercourse (dyspareunia).
  • Pain when you’re peeing or pooping.
  • Feeling the urge to pee more.
  • Back pain.
  • Vomiting.
  • Bloating.
  • Nausea.

Diagnosis and Tests

How are ovarian endometriomas diagnosed?

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.

What tests will be done to diagnose an ovarian endometrioma?

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:

  • A complete blood count (CBC): Your blood cells let your provider know if you have an infection or if you have too few red blood cells (anemia). People with ovarian endometriomas often have low red blood cell counts because of the heavy bleeding that comes with endometriosis.
  • A urinalysis: This test can let your provider know if your symptoms are from a urinary tract infection (UTI).
  • Sexually transmitted infection (STI) tests: Your provider can rule out whether an STI, like gonorrhea or chlamydia, is causing your symptoms.

Management and Treatment

Is there a cure for ovarian endometriomas?

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.

  • Monitoring: You and your provider may choose to monitor your cysts if they’re small and not causing symptoms.
  • Laparoscopy: Your provider may recommend a laparoscopy if you have ovarian endometriomas that are painful, growing or bigger than 4 centimeters. The risks increase that the cyst will become cancerous once it reaches this size. Removing the cyst not only helps improve your symptoms but it also reduces the risk that there’ll be continued damage to ovarian tissue, like having an ovarian endometrioma burst. It may improve your chances of becoming pregnant if you’ve had fertility issues because of ovarian endometriomas.
  • Hysterectomy/Oophorectomy: If other techniques haven’t improved your symptoms and you don’t have plans to become pregnant, your provider may recommend that you have your uterus (hysterectomy) and/or ovaries (oophorectomy) removed.

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.

What medications/treatments are used?

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:

  • Progestins.
  • Vaginal ring.
  • Birth control pills.
  • Birth control patch.
  • Gonadotropin-releasing hormone (GnRH agonist).

Your provider can suggest the best options available to you based on whether or not you’re trying to become pregnant.

What are the complications of the treatment for ovarian endometriomas?

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.


How can I prevent getting an ovarian endometrioma?

There’s no way to prevent endometriosis or endometriomas.

Outlook / Prognosis

What can I expect if I have an ovarian endometrioma?

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.

Living With

When should I see my healthcare provider?

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.

When should I go to ER?

You should seek emergency care if you have an ovarian endometrioma that bursts. Pay attention to these warning signs:

  • Fever.
  • Vomiting.
  • Feeling weak or dizzy, like you’re about to faint.
  • Severe pain in your abdomen that happens without warning.

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.

Medically Reviewed

Last reviewed on 11/02/2021.

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