What Are Endometrioid Cysts?

Medically Reviewed by Nivin Todd, MD on May 10, 2021
3 min read

Your endometrium is the lining of your uterus. Sometimes, for reasons that doctors don’t completely understand, this type of tissue can start to grow in other places like your fallopian tubes, bladder, or peritoneum (lining of pelvis and abdomen). If that happens, doctors call it endometriosis.

If the tissue gets to your ovaries, a cyst (lump) forms. That’s an endometrioid cyst, also known as an endometrioma. It is one kind of cyst that can form on the ovaries.

You could have only one, or you could have a cyst on each of your ovaries. While they’re often small (less than 2 inches), these cysts can grow as big as 8 inches across.

Endometriomas can:

The most common sign of endometriosis is pain in your lower belly that doesn’t go away. It can get worse before and during your period. You may also have very heavy bleeding. Pain during sex is likely.

Some women who have endometriosis feel sore or notice pressure. Others don’t have any symptoms at all. You may not know you have a cyst until your doctor feels it during a pelvic exam or sees it on ultrasound.

Your doctor will talk to you, listen to your symptoms, and ask about any pain you have. During a pelvic exam, they’ll press on areas in your belly. They may be able to feel a cyst this way.

Your doctor will probably want to do an imaging test to see inside your body. One way is with an ultrasound. It uses sound waves to create a picture. Magnetic resonance imaging (MRI) provides a more detailed view of your ovaries. It uses a powerful magnetic field.

Your doctor may also do a blood test to check for cancer, see if you’re pregnant, or if there’s an infection.

Another way to check for an endometrial cyst is through a laparoscopy. During this outpatient surgery, your doctor will make a tiny incision (cut) in your belly button and insert a thin camera. This allows your her to see any cysts up close, assess their size, and decide how best to treat them.

Your doctor will consider your age, any pain you’re in, and whether you plan to have a baby in the future. Based on that, they’ll choose a treatment plan that could include:

Watchful waiting. If you’re not in pain and the cyst is small, your doctor may suggest that you wait 6-8 weeks to see if it goes away on its own. They’ll use an ultrasound test to make sure this is happening.

Medicine. Your doctor may give you medicine to help shrink the cyst. A group of medications that doctors call “GnRH agonists” puts your body into temporary menopause. Your ovaries stop making estrogen, which can help ease any symptoms you have.

GnRH agonists can cause some of the same side effects as menopause, like hot flashes, bone density loss, and less sex drive. You shouldn’t take them if you’re trying to get pregnant.

Surgery. Your doctor may talk with you about surgery if you have intense pain, medicine doesn’t help, or your cyst is larger than 1.5 inches. They may choose this option to keep the cyst from twisting or breaking open, which can cause more severe problems.

Sometimes, the doctor may be able to drain the fluid in a cyst. In other cases, you may need to get the whole cyst taken out. This may ease your pain and prevent other cysts from growing.

If you’re sure that you never want to get pregnant, your doctor could remove your ovaries. Your uterus could be taken out as well, but doctors only do this procedure, called a hysterectomy, if nothing else helps. You and your doctor should talk about all of your options.

Show Sources


Brigham and Women’s Hospital, “Deep Ovarian Endometriosis (Endometriomas).”

UptoDate®: “Endometriosis: management of ovarian endometriomas,” “Patient education: Endometriosis: Beyond the Basics.”

Mayo Clinic, “Endometriosis.”

Radiology, “Endometrial cysts: diagnosis with MR Imaging.”

Medscape, “Ovarian Endometrioma.”

NHS, “Endometriosis,” “Ovarian Cyst.”

Radiopaedia.org, “Endometrioma.”

Current Obstetrics and Gynecology Reports: “Clinical Management of Ovarian Endometriotic Cyst (Chocolate Cyst): Diagnosis, Medical Treatment, and Minimally Invasive Surgery.”

American Society for Reproductive Medicine: “Endometriosis.”

The American Congress of Obstetricians and Gynecologists: “Endometriosis.”

UW Medicine: “Treatment for Ovarian Cysts.”

Korean Journal of Radiology: “CT Imaging Findings of Ruptured Ovarian Endometriotic Cysts: Emphasis on the Differential Diagnosis with Ruptured Ovarian Functional Cysts.”

The BMJ: “Magnetic resonance imaging.”

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