What is Chocolate Cysts?

Diagnosis of Chocolate Cyst

What is Chocolate Cysts?


A chocolate cyst of the ovary ( also known as an endometrioma, endometrioid cyst, or endometrial cyst) is found in some infertile women who have endometriosis. In this disease, the inner lining of the uterus ( called the endometrium ) grows in various abnormal locations within the pelvis . 

Bitter Humor? 

One of the commonest sites this aberrant endometrial tissue can be found in is the ovary. With every menstrual period, this tissue grows, enlarges , bleeds, and sloughs off . Here it forms a cyst; and because the contents of this cyst are black, tarry and thick, they resemble dark chocolate , hence the name ! ( I feel that sometimes doctors can have a perverse sense of humor. For most women, the word chocolate produces happy feelings, because chocolates are a woman's favourite treat. To label a disease condition after a dessert is something which only an unfeeling man would do ! )

Diagnosis of Chocolate Cyst

How is the diagnosis made ? While an alert doctor will often suspect the diagnosis in infertile women with progressively painful periods, often women with chocolate cysts may have no symptoms at all. This means this diagnosis is made during a regular infertility workup ; or even during a routine pelvic examination. While some cysts are large enough to be felt on pelvic examination, many are small and cannot be detected on clinical examination.


  • Ultrasound scanning is an excellent way of diagnosing chocolate cysts and can pick up cysts which are very small
  • On scanning, chocolate cysts are complex masses ( which have both solid and cystic components); and are often tender
  • They have a typical ground glass appearance because they contain old blood
  • They can vary in size from a few mm to over 10 cm; and can be bilateral
  • However, it's not possible to make a definitive diagnosis of endometriosis on ultrasound scanning, as many other conditions can also produce cysts in the ovary
  • The diagnosis can be confirmed either by aspirating the cyst under ultrasound guidance ( and finding the typical dark old blood which is diagnostic of endometriosis); or by doing a laparoscopy.

Other Tests

Many doctors will do a blood test for CA-125. This is a "cancer marker" and the levels are raised in women with ovarian cancer. They will find a high CA-125 level and cause the patient to panic by telling them they may have cancer and that they need surgery to rule out this possibility. This is not true. CA 125 is just a blood test - and levels are raised in many conditions, including endometriosis ! A high CA 125 does not mean you have cancer, so please do not worry needlessly.

Many doctors will also ask patients to do a MRI scan to evaluate the ovarian cyst . While this may be useful in a rare group of patients, usually the quality of information we get from a vaginal ultrasound is more than enough. An MRI usually does not change your treatment options and just adds to the costs !

In the past, a laparoscopy was the gold standard for making the diagnosis of endometriosis, as this allowed the doctor to actually inspect the pelvic contents. However, because it involves surgery, many infertility specialists no longer do a laparoscopy for their patients.  

Read more- Treating endometriosis in an infertile woman

Three Key Factors 

There are 3 key factors which doctors need to evaluate when making a decision as to how to treat chocolate cysts in infertile women.

  1. Whether the patient has any symptoms
  2. The size of the cyst
  3. The AMH level

Thus, when a small chocolate cyst is picked up when doing a routine vaginal ultrasound scan in a young asymptomatic infertile woman , the best course of action maybe masterly inactivity. This is because this is an incidental finding which is best documented and left alone. Remember that doctors do not treat ultrasound images - we treat patients !

Is Surgery Really Necessary?

Many fertile young women also have endometriotic cysts which they live with happily for all their lives ( and because they have enough sense not to go to a doctor, they often do not even know that they have a chocolate cyst !) Unfortunately, many doctors tend to be trigger-happy, and when they find a cyst on a pelvic ultrasound scan, they reflexly perform laparoscopic surgery - both to confirm the diagnosis; and to treat the cyst.

The danger is that this unnecessary surgery can actually reduce your fertility , as normal ovarian tissue is also removed along with the cyst wall, thus reducing your ovarian reserve. Small cysts ( less than 3 cm in size) can be happily left alone . If they are larger, they can be monitored by serial scans, before making a decision as to what the definitive treatment should be.

Treatment Options 

  • As regards treatment choices, the options include medical therapy or surgery. Medical therapy consists of medicines such as danazol or GnRH analogs to suppress the endometriosis; and while this is very effective in providing temporary symptom relief , it is not very effective in treating the cyst, which tends to remain inspite of the treatment
  • The definitive solution is surgical; and this usually consists of operative laparoscopy . Very few doctors will now do open surgery ( laparotomy) to treat a cyst, no matter how large it is.

The Controversies 

There are many controversies regarding the optimal surgical management of chocolate cyst s in an infertile woman, which is why it is important that you go to an expert. In the past , doctors would try to excise ( completely remove) the entire cyst , to reduce the risk of its recurring .

However, because this meant that they needed to also sacrifice normal ovarian tissue during this process, they often ended up pushing infertile patients from the frying pan into the fire by reducing their ovarian reserve and worsening their infertility !

The Conservative Approach 

This is why most doctors today prefer to be far more conservative in infertile women with chocolate cysts ; and will usually just create an opening in the cyst wall ( marsupialisation) to drain the contents. This often provides dramatic temporary relief. During the operative laparoscopy, the doctor also has an opportunity to remove the adhesions (scar tissue) and the other endometrial implants which are often found in women with chocolate cysts and treating these can also help to enhance their fertility for a few months.

The chances of achieving a pregnancy are maximal within a few months after the surgery. However, if a patient has failed to conceive within one year of the surgery, then the chances of success with repeat surgery are quite poor; and it's better to consider assisted reproduction.

The Tenacious Cysts 

The major bugbear with chocolate cysts is that they tend to recur. This is why doctors will often combine medical suppression with surgical treatment. However, all these are temporizing measures, which help to buy the patient time - we really do not have any way of curing this enigmatic disease !

The Aggressive Disease 

If the chocolate cyst recurs, patients are understandably upset, and feel that the doctor was incompetent and did not do a good job with the surgery. This is not always true, because endometriosis can be quite an aggressive disease in some women, and can recur even if the surgeon was very skilled. It's important to ask for DVD documentation of all surgical intervention, so that the video can be reviewed later on, if needed.

Excessive Surgeries 

If the cyst recurs, patients will often go to another surgeon ( who they feel is more expert) to try to correct the problem. The pelvis in some of these patients starts resembling a battle field, because they often end up having many laparoscopies done by many different surgeons, each of whom claims to be the best !

The surgery can be extremely challenging in these patients . The scarring , adhesions and previous surgery tend to distort the anatomy and the pelvis sometimes is completely frozen. Operative complications in these cases ( for example, inadvertently opening the bladder or rectum) are not uncommon.

The Important Factor 

The AMH level is a very important factor which many doctors tend to overlook in treating infertile women with endometriosis. The major danger with endometriosis is that the chocolate cyst replaces normal ovarian tissue, as a result of which many of these patients have little normal ovarian tissue and poor ovarian reserve as a result of their disease. This is why it's important to assess your ovarian reserve by checking your AMH level and your antral follicle count before doing anything further ! If your AMH level is low, then it's best to avoid surgery and to move on to IVF to maximize your chances of having a baby quickly ( before the disease becomes worse and eats away more of your precious reserve).

About IUI

For young women with normal ovarian reserve, open fallopian tubes ( as proven on HSG) and small chocolate cysts who have no symptoms, it's worth trying IUI before doing anything more aggressive. However , if the patient is symptomatic and the endometriosis is causing pain, then this become a trickier issue !

You need to set your priorities - is pain control more important ? Or is having a baby more important ? This is often a difficult decision to make, but you need to decide. It's best to make a list of all your options so you can think through these logically. If having a baby is key, then it's best to manage your pain symptomatically and concentrate your energies on getting pregnant quickly. IVF is very effective , as it maximizes your chances of getting pregnant quickly.

The Dual Benefit 

The beauty with IVF is that it allows you to kill 2 birds with one stone - not only do you get your deeply desired baby, you also have dramatic pain relief for at least 1 year ( because your periods will stop during your pregnancy and your postpartum period ).

As an added bonus, the endometriosis will also get better as a result of the pregnancy in some women ! This is why many doctors advise that the best treatment for a young woman with endometriosis is a pregnancy. Of course, this is easier said than done, because endometriosis does affect your fertility !

Read more- Should you treat the endometriosis before doing IVF ?


A chocolate cyst of the ovary ( also known as an endometrioma, endometrioid cyst, or endometrial cyst) is found in some infertile women who have endometriosis.

Authored by : Dr Aniruddha Malpani, MD and reviewed by Dr Anjali Malpani.

Open Video