Endometrioma:
Chocolate Cyst
Your guide to understanding and managing chocolate cysts - what they are, how they may affect you, and when it’s time to simply monitor or take action.
An endometrioma (commonly known as a chocolate cyst) is a type of cyst that forms when endometriosis affects the ovaries. They develop deep within the ovaries and are filled with old blood and endometrial-like tissue, giving them their characteristic dark, chocolate-like appearance.
Chocolate cysts can affect one or both ovaries, or nearby structures, and are most often seen in the later stages of endometriosis (moderate to severe). So if you’ve been told you have a chocolate cyst, it’s quite common for endometriosis to be part of the picture too.
What are the symptoms?
For some people, the symptoms may go unnoticed. But for many, chocolate cysts cause a range of symptoms that can significantly impact quality of life.
Pelvic pain
You might experience ongoing pelvic pain or discomfort that worsens during your period
Painful sex
Pain during or after sex is also common
Pain in the lower back
Lower back pain that can feel persistent and hard to pinpoint
Abdominal bloating
Some people notice a sense of bloating or fullness in the lower abdomen
Infertility
Some people may struggle with fertility, as chocolate cysts can affect ovarian function
A ruptured chocolate cyst can cause sudden and severe intense, one-sided abdominal pain, and in certain situations, it may require emergency medical care.
If you're experiencing any of these symptoms or have concerns about chocolate cysts, it's important to speak with a healthcare professional for evaluation and support tailored to you.
Diagnosis
Chocolate cysts are typically diagnosed using a combination of:
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Pelvic Exam - May reveal an enlarged ovary or tenderness.
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Ultrasound Scan - Often the first imaging tool used to detect cysts and assess their size, appearance, and impact on surrounding structures.
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MRI Scan - Offers more detailed imaging to help distinguish an endometrioma from other types of cysts.
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Laparoscopy - A minimally invasive surgical procedure that allows direct visualisation, diagnosis, and sometimes treatment.
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Kissing ovaries - The term 'kissing ovaries' is sometimes used on ultrasound when both ovaries are positioned very close together and appear to be touching. This often happens when chocolate cysts are present, causing the ovaries to stick to each other and lose their usual movement. The name comes from how they look gently pressed together, almost like a kiss.
In some cases, imaging may also reveal free fluid in the pelvis, which can indicate that a cyst has leaked or is beginning to resolve on its own. The body often absorbs this fluid naturally, but clinical follow-up is essential to ensure proper healing.
Between 20 and 40 percent of people with endometriosis develop chocolate cysts.
Chocolate cysts are not uncommon. As of mid-2023, the UK population was estimated to be approximately 68.3 million. Given that women made up around 51% of the population, this equates to roughly 34.8 million women living in the UK. If we consider the statistic that 1 in 10 women are affected by endometriosis, this would mean that around 3.48 million women in the UK are living with the condition.
Based on current estimates, 20-40% of those with endometriosis may develop ovarian endometriomas (chocolate cysts), which suggests that between approximately 696,000 and 1.39 million women in the UK could be affected by them.
Managing chocolate cysts:
When to Watch and When to Act
Chocolate cysts that are smaller and show signs of stability may simply require ongoing monitoring with repeat imaging. However, if a chocolate cyst grows beyond a certain size (typically greater than 4–5 cm), or if there are signs of infection or rupture, further intervention may be necessary. This can include:
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Antibiotics - if there is evidence of infection.
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Hormonal Treatments - to suppress endometriosis activity and potentially shrink the cyst.
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Surgery - The primary treatment for a chocolate cyst is surgical excision (removal of the cyst), especially if it’s causing significant pain, affecting fertility, or not responding to other options.
It’s important to understand that any treatment involving the ovaries can affect ovarian function and reserve. If you’re planning or hoping for a future pregnancy, it’s a good idea to speak with your medical team. They can help you explore all available options, including alternatives like cyst drainage or alcohol sclerotherapy.
Your medical team will work with you to guide you toward the approach that best supports your individual needs and future plans.
Treatment Options
Treatment of chocolate cysts depends on factors like the severity of symptoms, the size of the cyst, age, and whether the individual is trying to conceive. Options include:
Conservative
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In some cases, doing nothing and simply keeping an eye on symptoms can be a suitable option, especially if the cyst isn’t causing significant discomfort. If you choose a more conservative approach, regular follow-up scans are important. These help monitor for any signs of rapid growth, changes in the cyst, or worsening of pelvic endometriosis, ensuring that any necessary treatment can be considered at the right time.
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Hormonal treatments (e.g., birth control pills, GnRH agonists) to suppress endometriosis and reduce cyst growth.
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Pain management with NSAIDs (e.g., ibuprofen).
Surgical Treatment -
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Laparoscopic cystectomy (removal of the endometrioma) may be recommended, especially if the cyst is large, painful, or affecting fertility.
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Surgery may improve fertility outcomes but should be balanced with the potential risk of reducing ovarian reserve.
Fertility Support -
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Surgery may improve fertility outcomes but should be balanced with the potential risk of reducing ovarian reserve. An AMH test may be recommended prior to treatment.
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In cases of infertility, assisted reproductive technologies like IVF may be considered, especially if surgical removal of the chocolate cyst isn't advisable.
Potential Complications
If left untreated, chocolate cysts can gradually grow larger, often leading to more severe and persistent pain. In some cases, they may rupture, which can cause internal bleeding or trigger inflammation in the surrounding tissues. Over time, these cysts can affect ovarian function and may reduce fertility. They can also stick to nearby pelvic organs, leading to scarring and changes in the normal structure of the pelvis.
If you're experiencing any of these symptoms or have concerns about chocolate cysts, it’s important to speak with a healthcare professional for personalised advice and support.
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