Yes. Endometriosis can cause an ovarian cyst called an endometrioma, or “chocolate cyst.” It forms when tissue similar to the lining of the uterus grows on or in an ovary and blood collects over time. Not every ovarian cyst is linked to endometriosis, and an endometrioma may cause pain or no noticeable symptoms. An ultrasound and a clinician’s assessment can help identify what type of cyst may be present.
Endometriosis occurs when tissue similar to the lining of the uterus grows outside the uterus, often affecting the ovaries and other pelvic structures. When this tissue involves an ovary, it can lead to an endometrioma. Knowing how this type of cyst differs from other ovarian cysts can help explain why further testing or treatment may sometimes be recommended.
How can endometriosis lead to an ovarian cyst?
Endometriosis-related ovarian cysts are known as endometriomas. They are sometimes called chocolate cysts because they commonly contain thick, dark brown fluid made up of old blood. These cysts can develop on or within an ovary and may affect one or both ovaries.
The Mayo Clinic explains that endometriosis tissue can thicken and bleed in response to hormonal changes during the menstrual cycle. When this tissue affects an ovary, repeated bleeding and the buildup of old blood can contribute to cyst formation. The precise processes involved in endometriosis are not fully understood, so this explanation describes a possible mechanism rather than a complete account of every case.
Does every ovarian cyst mean someone has endometriosis?
No. Ovarian cysts have several possible causes, and many are not related to endometriosis. Some develop as part of the normal menstrual cycle, including cysts that form when an ovarian follicle does not release an egg as expected or when the structure left after ovulation fills with fluid.
According to the NHS, endometriosis is one condition that can cause blood-filled ovarian cysts. Other cysts may be unrelated to this condition. Their appearance, size, location, and changes over time can help a clinician assess which type is most likely.
Having an ovarian cyst does not, by itself, establish that endometriosis is present. Similarly, someone with endometriosis may have an ovarian cyst caused by a different process. The findings need to be considered alongside the person's medical history and any symptoms.
What symptoms can an endometrioma cause?
Some endometriomas cause no noticeable symptoms and are discovered during an imaging test performed for another reason. Others may contribute to pelvic discomfort or symptoms associated with endometriosis. The size and location of a cyst can affect the type of discomfort someone experiences, but symptoms alone cannot reliably identify the kind of cyst involved.
The American College of Obstetricians and Gynecologists (ACOG) describes symptoms of endometriosis that can include painful menstrual periods, ongoing pelvic pain, pain during sex, and pain with bowel movements or urination. These experiences may occur with endometriosis, including when the ovaries are involved, but they can also have other causes.
Symptoms that may warrant discussion with a healthcare professional include:
- Pelvic pain or tenderness that persists or keeps returning.
- Menstrual pain that interferes with normal activities.
- Pain during or after sexual intercourse.
- Discomfort during bowel movements or urination, particularly around menstruation.
- Pelvic symptoms that are becoming more frequent or disruptive.
The timing of symptoms can be useful information. For example, a clinician may ask whether discomfort occurs mainly during menstruation, at other points in the cycle, or throughout the month. Recording these patterns can help guide the assessment without determining the diagnosis on their own.
How do doctors check whether a cyst is related to endometriosis?
Assessment usually begins with a discussion of symptoms, menstrual history, previous diagnoses, medications, and pregnancy plans. A healthcare professional may also perform a pelvic examination when appropriate. These details help determine which tests are useful and whether the cyst needs closer evaluation.
A pelvic ultrasound is commonly used to examine the ovaries and assess a cyst's size, appearance, and location. A transvaginal ultrasound, which uses an ultrasound probe placed in the vagina, can provide detailed images of the pelvic organs. An abdominal ultrasound may also be used when appropriate.
The Mayo Clinic's guidance on endometriosis diagnosis explains that ultrasound can identify endometriomas, but a standard ultrasound cannot rule out all endometriosis or confirm every form of the condition. Magnetic resonance imaging (MRI) may be helpful in selected cases, including when more detail about the location and extent of abnormal tissue is needed.
Sometimes, additional evaluation or surgery is considered when imaging findings are uncertain or when the clinical situation calls for it. During laparoscopy, a surgeon uses a small camera to examine the abdomen and pelvis. Tissue may be collected for laboratory examination when appropriate. Not everyone with a suspected endometrioma needs surgery to establish a management plan.
How are endometriosis-related ovarian cysts treated?
Treatment depends on factors such as symptoms, cyst size and appearance, changes on follow-up imaging, medical history, and plans for future pregnancy. An endometrioma does not automatically need to be removed. Some smaller cysts that are not causing symptoms or concerning imaging findings may be monitored with follow-up appointments and ultrasound examinations.
The Cleveland Clinic describes monitoring, medication, and surgery as possible approaches to managing ovarian endometriomas. Hormonal medicines may help manage endometriosis-related pain, while surgery may be considered for cysts that cause persistent symptoms, grow, or raise other clinical concerns. The choice depends on the person's circumstances rather than on the presence of a cyst alone.
Before deciding on surgery, it is important to discuss the possible benefits and risks with a gynecologist. Surgery on an ovary can affect healthy ovarian tissue, so fertility goals may be especially relevant for someone who hopes to become pregnant. The possibility of recurrence and the need for follow-up care may also be part of the discussion.
Can an endometrioma affect fertility?
An endometrioma may be associated with fertility difficulties, but it does not mean pregnancy is impossible. The effect on fertility can depend on the cyst, whether one or both ovaries are involved, the extent of endometriosis, and other reproductive health factors.
For someone trying to conceive, treatment decisions may differ from those made primarily to relieve pain. Removing a cyst is not automatically the best option in every situation, because ovarian surgery can also affect ovarian function. A gynecologist or fertility specialist can discuss the potential benefits and drawbacks of monitoring, medication, or surgery in light of individual reproductive goals.
When does an ovarian cyst need urgent medical attention?
Seek urgent medical care if sudden, intense pelvic or abdominal pain develops. Pain accompanied by vomiting, fever, marked weakness, dizziness, or fainting also needs prompt assessment. These symptoms can occur with complications involving an ovarian cyst, including rupture or twisting of the ovary, and should not be assumed to be ordinary endometriosis pain.
The American College of Obstetricians and Gynecologists explains that ovarian cysts can sometimes bleed, rupture, or lead to twisting of the ovary. If symptoms are sudden or intense, do not wait for a routine follow-up appointment to seek care.
For ongoing pelvic pain or a cyst found on an imaging test, arrange a healthcare appointment to discuss the findings and appropriate follow-up. Understanding whether the cyst is likely related to endometriosis can help guide decisions about monitoring, symptom relief, and fertility planning.