Finding an ovarian cyst can be worrying, especially when you already have endometriosis. You may immediately wonder: can endometriosis cause ovarian cysts?

Yes. Endometriosis can cause a specific type of ovarian cyst called an endometrioma. These cysts form when endometriosis affects an ovary and are often filled with old, thickened blood. They are also commonly called “chocolate cysts” because of their dark brown appearance.

But there is an important catch: not every ovarian cyst is caused by endometriosis. Ovaries can develop several different types of cysts, many of which have nothing to do with endometriosis. Understanding that difference is the first step toward knowing what your scan actually means.

Can Endometriosis Cause Ovarian Cysts?

Yes, and the cysts associated with endometriosis are known as ovarian endometriomas.

Mayo Clinic puts it simply: “In some cases, endometriosis can cause cysts on the ovaries. These are called endometriomas.”

Endometriosis occurs when tissue similar to the lining of the uterus grows outside the uterus. The ovaries are one of the most common places affected. When endometriosis develops on or within an ovary, repeated bleeding and inflammation can eventually contribute to an endometrioma.

What Is an Endometrioma?

An endometrioma is an ovarian cyst associated with endometriosis. Unlike many simple ovarian cysts, it usually contains old blood and inflammatory material.

As blood accumulates over time, the cyst can become thick and brown, which explains the nickname “chocolate cyst.” An endometrioma can affect one ovary or, in some cases, both ovaries.

The important point is that an endometrioma is not simply a routine cyst caused by ovulation. It is a manifestation of ovarian endometriosis.

How Does Endometriosis Cause an Ovarian Cyst?

So, how does an endometriosis lesion turn into a cyst?

Think of it like a tiny patch of tissue that keeps reacting to your menstrual cycle in the wrong place. Endometriosis tissue outside the uterus can respond to hormonal changes, become inflamed and bleed. When this process involves the ovary, the blood and inflammatory material can become trapped, contributing to an endometrioma.

What Happens Inside an Endometrioma?

Over repeated menstrual cycles, old blood can accumulate inside the cyst. This is why endometriomas often look different from simple, fluid-filled ovarian cysts on imaging.

The surrounding ovary can also become inflamed. Over time, endometriosis may cause scar tissue and adhesions, which can distort the normal anatomy of the pelvis. This is one reason ovarian endometriomas can become more than just an isolated “cyst problem.”

Why Does Old Blood Build Up?

Unlike menstrual blood that leaves the body during a period, blood within an endometrioma remains trapped inside the ovarian cyst. With repeated bleeding, the contents become darker and thicker.

That gradual accumulation is what gives an endometrioma its characteristic appearance.

Are Endometriomas the Same as Regular Ovarian Cysts?

No. This is one of the most important points to understand.

An ovarian cyst is a broad term for a fluid-filled or partly fluid-filled structure that develops in or on an ovary. There are many types. Some occur naturally during ovulation and disappear without treatment. Others develop from different tissues within the ovary.

An endometrioma, however, is specifically associated with endometriosis.

RCOG explains that simple cysts are the most common ovarian cysts before menopause and that many disappear within a few months. It separately identifies endometriomas as ovarian cysts associated with endometriosis.

Common Types of Ovarian Cysts

Depending on your age and circumstances, an ovarian cyst may be:

• A functional cyst, related to the normal menstrual cycle
• An endometrioma, associated with endometriosis
• A dermoid cyst
• A cystadenoma
• Another less common type of ovarian mass

That is why hearing “you have an ovarian cyst” does not automatically mean you have endometriosis.

Endometrioma vs. Functional Ovarian Cyst

A functional cyst is often temporary. It may resolve naturally over one or several menstrual cycles.

An endometrioma is different. It develops in association with endometriosis and may persist, enlarge, cause pain, contribute to adhesions, or become relevant when fertility is a concern. Cleveland Clinic estimates that ovarian endometriomas occur in approximately 17% to 44% of people with endometriosis.

So, can endometriosis cause cysts on the ovaries? Absolutely—but the type of cyst matters.

What Are the Symptoms of an Ovarian Endometrioma?

Some people with an endometrioma have significant symptoms, while others may have surprisingly few. The presence of a cyst does not automatically tell you how much pain someone will experience.

Pelvic Pain and Period-Related Symptoms

Possible symptoms include:

• Pelvic or lower abdominal pain
• Painful periods
• Pain during or after sex
• Pain with bowel movements or urination
• Bloating
• Causes Back pain
• Nausea because of endometriosis
• Changes related to fertility

Cleveland Clinic notes that pelvic pain or tenderness is the most common symptom of an ovarian endometrioma, although symptoms can vary widely.

And here’s something patients often find confusing: the pain does not always occur only during your period. Endometriosis-related inflammation and adhesions can cause pelvic pain at other times too.

Fertility Problems and Other Possible Symptoms

Endometriomas may also be associated with fertility difficulties. Endometriosis can affect the ovaries, fallopian tubes and surrounding pelvic anatomy, while inflammation and adhesions may interfere with normal reproductive function.

That does not mean an endometrioma makes pregnancy impossible. Many people with endometriosis become pregnant, either naturally or with fertility treatment.

How Are Endometriomas Diagnosed?

Doctors usually combine your symptoms, medical history and imaging findings rather than relying on a single test.

Ultrasound and MRI

A transvaginal ultrasound is often an important first investigation for suspected ovarian endometriomas. It can help identify the cyst’s size, location and characteristic appearance. RCOG notes that transvaginal or transabdominal ultrasound can diagnose ovarian endometriomas, with reported detection rates of up to 90% for routine ultrasound.

MRI may be useful when doctors need additional information, particularly when disease is more extensive or the anatomy is difficult to evaluate. Imaging can also help with treatment planning.

When Is Laparoscopy Considered?

Laparoscopy is a minimally invasive surgical procedure that allows a specialist to look directly inside the pelvis. Depending on the circumstances, it can also allow treatment during the same procedure.

However, surgery is not automatically required simply because an endometrioma exists. Decisions depend on factors such as symptoms, cyst characteristics, fertility goals and the potential benefits and risks of intervention. NICE recommends individualized surgical discussions and specifically advises considering fertility and ovarian reserve when treating endometriomas.

How Are Ovarian Endometriomas Treated?

Treatment depends on the individual rather than simply the cyst measurement.

Medication and Monitoring

Hormonal treatments can help control endometriosis-related symptoms, particularly pain, but they do not simply erase an existing endometrioma.

For some patients, monitoring may be appropriate, especially when symptoms are manageable and there is no immediate reason to operate. Your specialist may recommend follow-up imaging and reassessment based on symptoms and changes over time.

Laparoscopic Endometrioma Surgery

When surgery is appropriate, laparoscopic ovarian cystectomy may be considered to remove the endometrioma.

NICE describes laparoscopic ovarian cystectomy as a surgical excision of an ovarian endometriotic cyst. Its guidance also stresses the importance of weighing the potential benefits against effects on ovarian reserve.

Surgery may become part of the discussion when an endometrioma is causing significant pain, contributing to infertility, changing over time, or occurring alongside more extensive endometriosis. The exact recommendation should come from a specialist assessment rather than a single cyst-size cutoff.

When Should You See an Endometriosis Specialist?

Consider specialist evaluation when you have:

• Persistent or severe pelvic pain
• A suspected or confirmed endometrioma
• Recurrent ovarian cysts with symptoms
• Difficulty becoming pregnant
• An enlarging or complex ovarian cyst
• Previous endometriosis surgery with recurring symptoms
• Imaging suggesting deep or extensive endometriosis

Urgent medical attention is appropriate for sudden, severe pelvic pain, especially when it is accompanied by vomiting, fainting, weakness or other acute symptoms, because ovarian cyst complications can occasionally require prompt assessment.

Dr. Lucas Minig’s Approach to Endometriosis and Ovarian Endometriomas

For patients seeking specialist care in Spain, Dr. Lucas Minig’s practice in Valencia focuses on individualized management of complex gynecological conditions, including endometriosis and ovarian endometriomas. His endometriosis treatment service includes laparoscopic removal of ovarian endometriomas, excision of deep endometriosis and adhesiolysis, with treatment planning based around symptoms and reproductive goals.

The clinic also describes a minimally invasive approach, with laparoscopic or robotic techniques used for most surgical procedures, alongside fertility-focused planning and multidisciplinary support.

This can be particularly relevant when an ovarian endometrioma is not an isolated finding but part of a broader pattern of pelvic endometriosis, adhesions or deep disease.

The goal should never be simply “remove the cyst.” The bigger question is: What approach gives you the best balance between symptom relief, disease control, ovarian preservation and your future fertility goals?

Conclusion

So, can endometriosis cause ovarian cysts? Absolutely. Endometriosis can affect the ovaries and form endometriomas, often known as chocolate cysts. These are different from common functional ovarian cysts and may cause pelvic pain, inflammation, adhesions and fertility difficulties.

But an ovarian cyst does not automatically mean endometriosis. Proper imaging and specialist assessment are important for understanding what type of cyst you have and whether treatment is necessary.

Most importantly, treatment should be individualized. For someone hoping to become pregnant, protecting ovarian reserve may be just as important as treating the endometrioma itself. Current guidance supports discussing the benefits and risks of medical management, monitoring and laparoscopic surgery according to the person’s symptoms, fertility plans and ovarian function.

FAQ’s

Can endometriosis cause cysts on both ovaries?

Yes. Endometriomas can affect one or both ovaries. Bilateral ovarian endometriomas can require particularly careful assessment because both ovaries may be involved.

Is an endometrioma the same as a normal ovarian cyst?

No. An endometrioma is specifically associated with endometriosis and often contains old blood. Functional ovarian cysts, by contrast, are commonly related to the normal menstrual cycle and may disappear without treatment.

Can an ovarian endometrioma go away on its own?

Endometriomas are different from many temporary functional cysts, so they should not be assumed to disappear on their own. Whether an endometrioma should be monitored or treated depends on factors such as symptoms, size, fertility plans and ovarian reserve.

Does an endometrioma mean I cannot get pregnant?

No. An endometrioma may affect fertility, but many people with endometriosis become pregnant. When fertility is a priority, treatment decisions should take ovarian reserve and other fertility factors into account.

Does every endometrioma need surgery?

No. Surgery is not automatically necessary for every patient. Depending on the circumstances, monitoring, medical management or laparoscopic treatment may be considered.