What is Chocolate Cyst? (Ovarian Endometrioma)

chocolate cysts & endometrioma

What is Chocolate Cyst? (Ovarian Endometrioma)

“Chocolate cyst”, also called Ovarian Endometrioma, is a type of benign ovarian cyst which forms when cells from the internal lining of the uterus (called endometrium) are found within the ovary, forming a dark old blood fluid-filled sac or cyst that appears like chocolate. It is commonly associated with severe endometriosis. Up to a third of women with symptoms of endometriosis are found to have endometrioma. Endometrioma is usually detected as a cyst formation within the ovary through an ultrasound scan. It has the typical appearance of ‘ground glass’. Pelvic ultrasound scan done through specialist gynaecological sonologist experienced in endometriosis scanning can help in more accurately determining the type of ovarian cyst. There is commonly other associated endometriosis within other parts of the pelvis.


chocolate cysts & endometrioma

How does Chocolate Cyst (Ovarian Endometrioma) affect you?

Endometrioma may be found incidentally on an ultrasound scan performed for unrelated symptoms. It may be small and does not cause any symptoms such as pain. Endometrioma is commonly detected when an ultrasound scan is done to investigate pelvic pain. As a severe form of endometriosis, endometrioma can cause pain within the pelvis, which may be worse during menstrual periods. It may also be detected during investigation for subfertility. Endometriosis and endometrioma are associated with reduced fertility. It is also important to rule out potential cancerous changes within any detected ovarian cyst.


Symptoms & Causes, Try to seek a medical professional if you’re unsure.

The exact cause of ovarian endometriomas, a type of endometriosis, is not completely understood by doctors. However, the prevailing theory is known as retrograde menstruation. This occurs when endometrial-like tissue, instead of exiting the body through the vagina during menstruation, flows backwards through the fallopian tubes into the ovaries. With each menstrual cycle, hormones prompt this misplaced tissue to bleed, causing inflammation. Over time, the accumulation of menstrual blood and inflamed tissue can lead to the formation of an ovarian endometrioma.

The primary indicator of an ovarian endometrioma is pelvic pain or tenderness. Additionally, you might experience a range of other symptoms including:

  • Severe pain during menstrual periods.
  • Discomfort during sexual activity (dyspareunia).
  • Painful sensations during urination or bowel movements.
  • Frequent urges to urinate.
  • Backache.
  • Vomiting.
  • Abdominal bloating.
  • Nausea.




How is Ovarian Endometrioma treated?

Treatment of endometrioma needs to be individualised to the patient – dependent on the patient’s age, symptoms and treatment goals. Each treatment option comes with potential side effects and risks that need to be balanced against its benefits.

Incidental small endometrioma that does not cause any symptoms can be monitored conservatively. While large endometrioma that causes pain may need to be removed surgically. The risks and benefits of surgically removing endometrioma in someone with subfertility must be considered before deciding on treatment. Hormonal treatment such as contraceptive pills, progesterone treatment through oral medications or intrauterine devices may also be recommended to reduce the chance of endometrioma and endometriosis recurring in future. Hormonal treatment does not remove the cyst itself and is used in the long term.

Things to consider before undergoing surgery for Chocolate Cyst

Is the surgery to remove endometrioma necessary?
What’s the goal of the surgery?
Surgery may be indicated if the endometrioma is large (usually more than 3-4cm in size), causes significant pain, or is suspicious for cancerous change on imaging. Surgical removal of endometrioma may improve fertility. It may also be recommended prior to egg pick up as having endometrioma can increase the risk of infection during egg pickup for fertility treatment. This has to be weighed against the risk of reducing ovarian reserve when surgery is performed to remove endometrioma from an ovary.

Surgical removal of endometrioma is usually performed through laparoscopic ‘keyhole’ surgery. This is associated with smaller risks of bleeding, infection and adhesions (internal scar tissue) compared to traditional open-cut surgery. Laparoscopic surgery also shortens hospitalisation (usually done as a day procedure) and recovery time.



Unfortunately, there is no known method to completely prevent endometriosis or ovarian endometriomas.

Outlook / Prognosis

Ovarian endometriomas indicate a more severe form of endometriosis. It is crucial to collaborate with your healthcare provider to manage symptoms effectively. Treatment may include addressing pain and fertility concerns, particularly if you are trying to conceive. Post-surgery, it’s important to remain vigilant as approximately 25% of women may experience a recurrence of ovarian endometriomas. The positive aspect is that symptoms generally improve with menopause, which reduces the hormonal fluctuations associated with menstruation.

Living With Ovarian Endometrioma

Regular consultations with your healthcare provider are essential for monitoring ovarian endometriomas, especially if they grow larger than 4 centimeters or increase in size, as they might pose a risk of becoming cancerous. Additionally, consult your provider if you experience pain to discuss your treatment options.

Emergency Situations

Immediate medical attention is necessary if an ovarian endometrioma ruptures. Watch for critical symptoms such as fever, vomiting, severe sudden abdominal pain, or feelings of weakness or dizziness that could indicate fainting.