Endometrioma (Chocolate Cyst): Symptoms, Diagnosis and Treatment Options

Receiving a diagnosis of a chocolate cyst, or finding an unexpected result on a pelvic scan, can feel unsettling. You may have questions about what this means for your health, your fertility, and your daily life.

What Is an Endometrioma (Chocolate Cyst)?

An endometrioma is a type of ovarian cyst that forms when endometrial-like tissue (tissue similar to the lining of the womb) grows outside the uterus and attaches to one or both ovaries. Over time, this tissue bleeds with each menstrual cycle, and the old blood collects inside the cyst. Because this blood breaks down into a thick, dark fluid, the cyst takes on a chocolate-brown appearance, which is how it earned the name “chocolate cyst.”

Endometriomas are directly linked to a condition called endometriosis, where endometrial-like tissue grows in places it should not, such as on the ovaries, fallopian tubes, or other pelvic structures. An endometrioma is one of the more visible manifestations of endometriosis, and it is important to understand this connection when thinking about treatment.

The cysts themselves are not cancerous in most cases, and many women with endometriomas are able to manage the condition with appropriate care.

How Endometriomas Develop

Normally, the lining of the uterus builds up and sheds with each menstrual cycle. In endometriosis, similar tissue ends up outside the womb, including on the surface of the ovaries.

Each month, this misplaced tissue responds to hormonal changes just as the womb lining does. It thickens, then bleeds. But unlike the womb, there is no exit route for this blood. On the ovary, the blood gradually accumulates and becomes enclosed within a cyst wall. Over successive menstrual cycles, the cyst may grow larger as more old blood collects inside it.

This slow, cyclical process is why endometriomas tend to grow gradually over time rather than appearing suddenly.

How Common Are Chocolate Cysts in Singapore?

Endometriosis affects a proportion of women of reproductive age globally, and endometriomas represent one of the more frequently encountered forms of the condition. In Singapore, women may first discover a chocolate cyst during a routine pelvic ultrasound, a fertility assessment, or an investigation for pelvic pain. Because awareness of endometriosis has grown in recent years, more women are receiving earlier diagnoses, which may open up a broader range of management options.

Symptoms of Endometrioma

Endometriomas do not affect every woman in the same way. Some women experience significant, life-disrupting symptoms, while others have no symptoms at all.

Pelvic Pain and Painful Periods

Pelvic pain is one of the more commonly reported symptoms associated with endometriomas. This pain may feel like:

• A dull, persistent ache in the lower abdomen or pelvis
• Cramping that is noticeably worse than usual during menstruation
• Pain that begins a few days before your period and lingers after it ends
• A feeling of heaviness or pressure in the pelvic area

Painful periods (a condition doctors call dysmenorrhoea) that progressively worsen over time are a particularly important sign to discuss with a gynaecologist. Worsening menstrual pain is worth investigating.

Pain During Intercourse

Some women with endometriomas experience pain during or after sexual intercourse, known medically as dyspareunia. This may occur because the cysts and surrounding scar tissue can make the pelvic structures less flexible and more sensitive to pressure. It is a recognised symptom, and there is no need to feel embarrassed about raising it with your doctor.

Fertility Concerns Linked to Chocolate Cysts

Endometriomas may affect fertility in several ways. They may:

• Reduce the reserve of healthy eggs in the affected ovary
• Cause inflammation that affects egg quality
• Create adhesions (bands of scar tissue) that can interfere with the function of the fallopian tubes

If you are planning a pregnancy and have been diagnosed with an endometrioma, you may wish to discuss your fertility goals early with your specialist. Many women with endometriomas do conceive, particularly when the condition is identified and managed with fertility goals in mind.

When There Are No Symptoms at All

It is entirely possible to have an endometrioma and feel nothing unusual. Many chocolate cysts are discovered incidentally during an ultrasound performed for an unrelated reason. An incidental finding does not automatically mean you need immediate treatment.

How Are Endometriomas Diagnosed?

Your gynaecologist will typically use a combination of tools to build a clear picture of your situation.

Pelvic Ultrasound and Imaging

A pelvic ultrasound is usually the first step in diagnosing an endometrioma. A transvaginal ultrasound (where a small, smooth probe is gently placed inside the vagina to get a clearer image of the ovaries and uterus) provides a detailed view of the pelvic organs. Endometriomas have a characteristic appearance on ultrasound, often described as a homogeneous, ground-glass texture, which helps distinguish them from other types of ovarian cysts.

An MRI scan (magnetic resonance imaging) may occasionally be recommended to provide more detailed information, particularly if the ultrasound findings are unclear or if multiple cysts are present.

Blood Tests and the Role of CA-125

CA-125 is a protein that can be elevated in the blood of women with endometriosis and endometriomas. A blood test measuring CA-125 levels may be used as part of the assessment. However, CA-125 is not a definitive diagnostic test on its own. It can be elevated for various reasons, and some women with endometriomas have normal levels. Your doctor will interpret this result alongside your other findings.

When Laparoscopy Is Needed for a Definitive Diagnosis

Laparoscopy (keyhole surgery) is considered a definitive way to diagnose endometriosis and endometriomas. During this procedure, a surgeon inserts a thin camera through a small incision in the abdomen to directly visualise the pelvic organs. It allows the surgeon to confirm the diagnosis, assess the extent of the condition, and in many cases, treat the cyst at the same time.

Laparoscopy is performed under general anaesthesia and is not typically the first step unless imaging findings are inconclusive or surgical treatment is being considered.

The following table provides a summary of common diagnostic methods.

Endometrioma Treatment Options

Treatment for endometriomas is not one-size-fits-all. A gynaecologist will consider a range of factors, including the size of the cyst, the severity of your symptoms, your age, and whether you are planning a pregnancy.

Watchful Waiting and Monitoring

For small endometriomas that are not causing symptoms, a period of watchful waiting may be recommended. The cyst is monitored regularly through ultrasound scans to track any changes in size or appearance. This approach may be appropriate when the cyst is stable and the risks of intervention outweigh the potential benefits.

Monitoring involves maintaining a consistent relationship with your specialist so that any changes can be reviewed in a timely manner.

Hormonal Therapy to Manage Symptoms

Hormonal medications can help manage the symptoms associated with endometriomas by reducing or suppressing the hormonal fluctuations that may drive the growth of endometrial tissue. Options may include:

• The combined oral contraceptive pill
• Progestogen-only medications
• The hormonal intrauterine system (hormonal coil)
• GnRH analogues (medications that temporarily reduce oestrogen levels)

Hormonal therapy does not eliminate an existing endometrioma, but it may slow its growth and help reduce pain in some women. It is often used as a longer-term management strategy, particularly for women who are not planning an immediate pregnancy.

Surgical Removal of Chocolate Cysts

Surgery may be recommended when the cyst is large, causing significant symptoms, or affecting fertility. The aim of surgery is typically to remove the cyst while preserving as much healthy ovarian tissue as possible.

Minimally Invasive Surgery for Endometriomas

Laparoscopic surgery, commonly known as keyhole surgery, is a widely used approach for removing endometriomas. The surgeon operates through small incisions in the abdomen using a camera and fine instruments, rather than making a large open cut.

Compared with open surgery, this approach is generally associated with:

• Smaller incisions and less visible scarring
• Reduced post-operative discomfort
• A shorter hospital stay, often just one to two days
• A faster return to daily activities for many women

Laparoscopic surgery for endometriomas requires a specialist with experience in this technique. Dr Harvard Lin is an Obstetrician and Gynaecologist who focuses on minimally invasive surgery and endometriosis, with clinical experience in this area of care.

Balancing Treatment with Fertility Preservation

For women who wish to conceive, treatment decisions require careful thought. Surgical removal of an endometrioma carries a small risk of reducing the ovarian reserve (the number of eggs available), particularly if surgery is performed on both ovaries or if the procedure is repeated. A specialist may discuss the timing of surgery in relation to your fertility plans, and in some cases, referral to a fertility specialist may be appropriate.

Treatment decisions depend on your individual circumstances, and the table below is intended as a starting point for discussion with your specialist rather than a definitive guide.

Why Timely Assessment May Be Worth Discussing with a Specialist

Having an endometrioma assessed in a timely manner may give you and your specialist the information needed to make considered decisions. Early evaluation may help support the management of your ovarian reserve, address symptoms, and ensure that any changes in the cyst are identified and reviewed.

Can Endometriomas Come Back After Treatment?

Endometriomas can recur after treatment, including after surgical removal. Several factors may influence the likelihood of recurrence:

• The extent of the underlying endometriosis at the time of surgery
• Whether hormonal therapy is used after surgery to suppress regrowth
• The woman’s age and hormonal status
• Whether both ovaries were affected

Recurrence reflects the nature of endometriosis as a condition driven by ongoing hormonal activity. Regular follow-up with a gynaecologist is important after treatment, both to monitor for recurrence and to adjust the management plan as circumstances change.

Many women find that a combination of surgical treatment followed by longer-term hormonal therapy may support sustained symptom relief, though individual responses vary.

Living with Endometrioma: Practical Tips for Day-to-Day Wellbeing

Some practical considerations that many women find helpful include:

• Heat therapy: A warm compress or heat pad applied to the lower abdomen may help ease pelvic discomfort during flare-ups.
• Gentle movement: Light exercise such as walking or yoga may help with pain management and mood. You may wish to follow your doctor’s guidance around activity levels, particularly after surgery.
• Nutritional awareness: Some women find that reducing inflammatory foods (such as processed foods and excess sugar) supports their overall wellbeing, though dietary changes should complement, not replace, medical treatment.
• Emotional support: Living with a chronic condition can be emotionally taxing. Connecting with a counsellor, a support group, or trusted people in your life can make a meaningful difference.
• Consistent follow-up: Keeping your scheduled appointments allows your specialist to track the condition over time and adjust your plan as needed.

Taking an Active Role in Your Endometrioma Care

You may find it helpful to:

• Write down your symptoms before appointments, including their frequency, severity, and any patterns you notice
• Ask your doctor to explain any terms or recommendations you do not fully understand
• Raise your fertility goals early, even if pregnancy is not an immediate plan
• Request a clear explanation of what monitoring will involve and how often you will be reviewed

When to Seek Professional Help

• Persistent or worsening pelvic pain, particularly around your menstrual cycle
• Pain during intercourse that is affecting your quality of life
• Difficulty conceiving after a reasonable period of trying
• Sudden, severe pelvic pain (which could indicate a cyst has ruptured or twisted, a situation that warrants prompt medical attention)
• An incidental finding of an ovarian cyst on imaging, even if you have no symptoms
• A change in your symptoms if you have already been diagnosed with an endometrioma, including new or intensified pain

Commonly Asked Questions

How long can a chocolate cyst be left untreated?

Small, asymptomatic endometriomas may be monitored over time without active treatment in some cases. However, ongoing specialist review is important to assess whether the cyst is growing or changing. The appropriate approach to monitoring depends on your individual circumstances, and your gynaecologist will advise you based on regular assessments.

Can endometriomas affect my chances of getting pregnant?

Endometriomas may affect fertility by reducing ovarian reserve (the pool of available eggs) and by causing inflammation that may affect egg quality. That said, many women with endometriomas do conceive, particularly when the condition is identified and managed with fertility goals in mind. Discussion with your specialist about your reproductive plans may be worth considering.

Is surgery always necessary for a chocolate cyst?

Surgery is not always the first or only option. For smaller cysts or those that are not causing symptoms, watchful waiting or hormonal therapy may be appropriate. The decision to proceed with surgery depends on the size of the cyst, the severity of your symptoms, and your fertility goals. A healthcare professional can help determine the most suitable approach for your situation.

Can chocolate cysts become cancerous?

The risk of an endometrioma undergoing malignant transformation (becoming cancerous) is considered low, around 1%. However, regular monitoring is recommended to detect any changes in the cyst’s appearance or behaviour. If your doctor recommends follow-up scans, this is a precautionary measure and not necessarily an indication that something is wrong.

What is the difference between an endometrioma and other ovarian cysts?

Not all ovarian cysts are the same. Functional cysts form as part of the normal menstrual cycle and often resolve on their own. Dermoid cysts contain different types of tissue such as hair or skin cells and are unrelated to the menstrual cycle. Endometriomas are associated with endometriosis and contain thick, dark brown material often described as old menstrual blood. The type of cyst is relevant because it influences the most appropriate monitoring strategy and treatment approach.

Next Steps

If you have been diagnosed with an endometrioma, or if you are experiencing symptoms that concern you, speaking with a gynaecologist who can review your specific situation may be a helpful next step. Bringing a note of your symptoms, any previous scan results, and your questions can help make the most of your consultation.

Speak with a Gynaecologist About Your Concerns

If you have received an endometrioma diagnosis or are experiencing pelvic symptoms that have not yet been investigated, a consultation with a gynaecologist in Singapore may provide useful clarity and guidance.