An Overview of Endometrioma

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An endometrioma, also called ovarian endometrioma or endometrioid cyst, is a type of cyst formed when endometrial tissue grows in the ovaries. These cysts are benign and estrogen-dependent. An endometrioma which is filled with old blood is called a chocolate cyst. While they sound scary, chocolate cysts are actually common, and benign.

An endometrioma is part of a condition known as endometriosis. Endometriosis is a painful condition in which endometrial tissue grows outside the uterus.  

The endometrium is the tissue which lines the uterus. It responds to the hormonal changes of the menstrual cycle. Over the course of about a month (28-30 days), the endometrium gets fuller and thicker, and blood flow in the tissue increases. The process gets the uterus ready to have a fertilized embryo implant in the endometrial tissue when pregnancy occurs. After about 28 days, if there is no pregnancy, the thickened endometrium is shed, which is the woman's menstrual period.

Endometriosis also responds to the hormonal changes of a woman's menstrual cycle. Because the tissue is not located in the uterus, it can cause excruciating pelvic pain associated with menstruation. Pain can also occur between menstrual periods. Some women with endometriosis may have fertility problems. 

Endometriosis affects up to 15% of women of reproductive age, with up to 8% experiencing the growth of at least one endometrioma. An endometrioma is often associated with more severe forms of endometriosis.

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An endometrioma may cause symptoms for some women. The size of the cyst does not determine the type of symptoms or the severity of symptoms. In other words, a woman who has a small cyst can experience severe pain, or a woman with a large cyst might have no symptoms or just mild symptoms. An endometrioma rarely exceeds 20 centimeters in size; most are 2-5 cm.

When endometrioma symptoms do occur, they are similar to the symptoms of endometriosis. These may include:

  • Painful periods
  • Pelvic pain not related to monthly periods
  • Irregular, and sometimes heavy periods
  • Pain during sexual intercourse
  • Infertility for some women


There are potential complications:

  • Infertility
  • Cancer, rarely, after menopause
  • Obstruction of the urinary tract or bowel
  • Debilitating, chronic pelvic pain
  • Large cysts, which could rupture

Signs of a ruptured cyst include:

  • Intense abdominal and/or pelvic pain: Pain will be sharp and sudden or numbing in the lower abdominal area on the side of the ruptured cyst.
  • Bleeding: Ruptured cysts are known for happening during monthly periods, and as a result, they may be missed. If bleeding during your period is significant and you are experiencing severe pain, immediately talk to the doctor who is treating you for endometriosis.
  • Dizziness, nausea, vomiting, and low-grade fever are all common symptoms of a ruptured cyst.

Up to half of people with endometriosis are infertile, but why is not known. Infertility theories include:

  • Inflammation, which produces chemicals called cytokines. These cytokines can interfere with the functions of the sperm and egg cells, making fertilization more difficult.
  • Adhesions (tissues stuck together) and scarring from endometriosis or previous pelvic surgery can block the fallopian tubes or uterus, making it difficult for the sperm and eggs to meet.
  • Endometrial tissue stuck to the ovaries can prevent release of an egg.


Researchers don’t know for sure what causes endometrioma. One theory is that endometriomas form due to retrograde menstruation, which may also explain endometriosis.

According to the Endometriosis Foundation of America, retrograde menstruation refers to a women’s menstrual blood flow going back into her body during her period.

The retrograde menstruation carries endometrial cells backward through the fallopian tubes to the ovaries and pelvic cavity, where they implant and cause endometriosis to develop.

Endometrial cells which attach and implant into the ovaries cause cysts to develop, in other words, endometriomas. The lining of these cysts behaves in the same way the lining of the uterus does. It grows and sheds monthly in response to female hormones. However, instead of leaving the body, endometrial tissue is trapped in the cysts, causing inflammation, and changing the way the ovaries function.


Your doctor may suspect endometriomas if you have endometriosis and are experiencing symptoms or have unexplained infertility. A cyst can also be felt during a pelvic exam.


Ultrasounds are good at identifying the presence of cysts, but they are not helpful in determining the type of cyst.


To confirm if a cyst is endometrioma, your doctor will want to test fluid and debris drawn from the cyst with a needle.

During the biopsy, your doctor will use ultrasound to help guide the needle through the vagina to the endometrioma. The fluid and tissue samples are then examined under a microscope to determine if they contain endometrial cells, which is a key indicator of endometrioma.


How your doctor treats endometriomas depends on several factors. These factors may include your age, symptoms, whether one or both ovaries are affected, and your plans for having children. 

Observation and Monitoring

Small cysts that are not causing symptoms are usually not treated. Instead, your doctor will want to take a watch-and-wait approach. 


Birth control pills may be recommended to manage pain, suppress ovulation, and to slow down the growth of cysts. Most birth control pills use a combination of the synthetic forms of the hormones estrogen and progestin.

For endometriosis, birth control pills that use higher levels of progestin are the most effective for stopping endometriosis pain. Continuous use of birth control pills to prevent menstruation can stop endometrial cells from shedding, then causing inflammation and irritation.

Birth control pills that are monophasic, which release a continuous, steady, dose of hormones each day of the month, are most useful for alleviating the symptoms of endometriosis. The monophasic pills do not have 1 week free of hormones of a 4-week cycle of pills.

Slowing down cyst growth will not keep cysts from growing or new ones from developing. Even after surgery, some women may experience new cyst growth.


Surgery to remove cysts—called ovarian cystectomy—is recommended for women who have painful symptoms, large cysts, cysts that might be suspect for cancer, and infertility. This procedure is done using a laparoscope, a thin, long tube with a camera and light to help the doctor perform the procedure. The laparoscope is inserted through a small incision just below a woman's naval.

Ovarian cystectomies can potentially contribute to infertility, and negatively affect ovarian function. The pros and cons of this procedure must be weighed. For some women, the inflammation and toxicity of having an endometrioma are more harmful than risking infertility.

There is also the potential for malignancy in tumors greater than 4 centimeters. Surgery is also recommended in cases in which a woman is in severe pain.



In recent years there has been a lot of interest in the role of inflammation in many diseases. Diet can affect inflammation, so diet may affect endometriosis, a disease in which inflammation may have a role.

A higher intake of fresh fruits and vegetables has been shown to decrease the risk for endometriosis by 40 percent. A higher consumption of red meat increases the risk of endometriosis.

It is suggested that boosting the intake of omega-3 fatty acids can decrease the risk for endometriosis. Some foods high in omega-3 fatty acids are salmon, flaxseeds, and walnuts.

Exercise Regularly

Exercise may help women cope with endometriosis in a number of ways. It encourages healthy circulation, decreases estrogen production, relieves stress, and releases pain-relieving endorphins in the brain.

Managing Stress

Endometriosis contributes to stress, because the pain and other symptoms affect all aspects of life, including work, family, and relationships. Reducing stress will improve your quality of life.

Some complementary or alternative therapies help some women, but are not studied thoroughly. These include acupuncture, herbal medicines, vitamins, and dietary supplements.

Before using alternative treatments discuss them with your healthcare provider.


Question 1. What kind of doctor treats an endometrioma? Gynecologists treat endometriosis the most.

Question 2. How fast does an endometrioma grow? Their size waxes and wanes with the hormonal changes of a woman's menstrual cycle.


Question 1. What kind of doctor treats an endometrioma? Gynecologists treat endometriosis the most.

Question 2. How fast does an endometrioma grow? Their size waxes and wanes with the hormonal changes of a woman's menstrual cycle.

A Word from Verywell

Endometrioma is common in women who have endometriosis. Your symptoms can usually be managed with medication, and surgery is an option when medication does not help.

Endometriomas and surgical treatments may affect fertility. Talk to your doctor about all your treatment options. Let your doctor know if you are considering having children in the future. All these things help with developing an appropriate treatment plan.

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