Endometriomas

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This is a type of cyst caused by endometriosis on the ovary. They are often known as “chocolate cysts” because they contain brown liquid inside of them that resembles chocolate syrup.

Hormonal suppression doesn’t resolve endometriomas

Endometriomas can be responsive to ovarian hormones, therefore some people taking a wait-and-see approach to their endometrioma may decide to go on hormonal suppression with the goal of suppressing ovarian activity to try and reduce pain and inflammation. Endometriomas may or may not progress in size with or without medical treatment. If one is taking a wait-and-see approach (whether they are on hormonal suppression or not), they can routinely monitor their endometriomas via ultrasound.

When a person is taking hormonal suppression, there may also be a temporary reduction in size due to decreased inflammation. However, in the studies looking at this, endometrioma reduction was not uniform in all patients or predictable. Some patients saw no reduction and in fact, some continued to see their endometrioma grow while on hormones. If the endometrioma does have a reduction, once a person goes off the medication, the endometrioma often increases in size again. This may be helpful to some patients looking to delay the need for surgery for their endometrioma, but keep in mind that endometriomas don’t resolve with medical treatment.

Various studies have shown that endometriomas are rarely found by themselves. Typically a person with an endometrioma has more areas of endometriosis, so an endometrioma having a slight decrease in volume doesn’t change the rest of your lesions or their severity. Depending on the size and the endometrioma itself, it can be stuck to the rectum, ureters, the uterus, the other ovary, etc. It can take an hour or more to remove the endometrioma, and then the rest of the surgery has to begin! 

Surgical treatment of endometriomas

Medical treatment (Dienogest, Lupron, Orilissa, birth control) doesn’t resolve endometriomas, so surgical treatment is typically necessary.

What surgical technique to use?

There are various ways to surgically treat an endometrioma, including drainage, ablation, excision, and sclerotherapy.

Excision of an endometrioma is generally preferred. Both the 2022 European endometriosis guidelines as well as ACOG guidelines state that studies show that excision of an endometrioma has lower recurrence rates of endometriosis-associated pain and of the endometrioma itself compared to drainage and ablation of the cyst wall. However, surgery may lower AMH, damage the ovary, or reduce ovarian reserve, so it’s important to:

• see an expert excision surgeon with the necessary skills to operate on an endometrioma.

“The level of expertise in endometriotic surgery is inversely correlated with inadvertent removal of healthy ovarian tissue along with the endometrioma capsule.” (1)

• have a conversation with the surgeon about your treatment goals, even if fertility isn’t a concern.


Do I need to remove my ovary?

No. In general, you shouldn’t need to remove an ovary for an endometrioma. Your ovaries play an important role in your body, and removing an ovary (even if you still keep one) can have negative hormonal consequences. If you are thinking about removing an ovary, you should evaluate the pros and cons of this. For me personally, removing one ovary is a medical decision I strongly regret. 

When to operate?

Some doctors prefer to wait until endometriomas reach a certain size, such as 4 cm, before operating. Others will operate depending on a patient’s pain or fertility goals. 

“Endometriomas of 6 cm or more in diameter may be associated with increased risks for infection, rupture, and even malignancy, and therefore, surgical intervention is considered obligatory.” (1)

While surgery may lower AMH, damage the ovary, or reduce ovarian reserve, an untreated endometrioma may also do the same.

“Brosens et al. reported that…[endometriomas are] associated with inflammation independent of the lesion’s size, leading to fibrosis of the ovarian cortex, smooth muscle cells metaplasia, and loss of oocytes.” (1)

Speak to your qualified surgeon about your treatment goals, symptoms, and what/when treatment is right for your individual case.

Endometriomas have a higher recurrence rate

Endometriomas have a higher risk of recurrence than other types of endometriosis, even in the hands of an expert. And when they are not excised (and instead are drained and the cyst wall ablated), the rate of persistence (endometriosis remaining because it was never properly removed in the first place) is even higher.

However, it’s important to know that if your endometrioma recurs, this doesn’t mean that your endometriosis in other areas has also recurred.

Hormonal suppression and endometrioma recurrence

Some studies done on endometriomas suggest that taking hormones post excision can sometimes help to slow potential endometrioma recurrence for some people. (Important note: I’m speaking here about endometrioma recurrence, and not recurrence of superficial or deeply infiltrating endometriosis).

Closer look at the study “Long-term adjuvant therapy for the prevention of postoperative endometrioma recurrence: a systematic review and meta-analysis”

A systematic review and meta-analysis by Vercellini et al (2) looked at 4 studies comparing use of oral contraceptives (OC) post excision of an endometrioma vs. expectant management (no use of oral contraceptives). The period of OC use varied from 24 to 35 months. Patients were monitored for endometrioma recurrence via ultrasound (endometriomas of at least 1.5 cm in one study or 2 cm in 3 studies) and/or histological confirmation.

Across the 4 studies, there were a total of 965 patients enrolled (726 in three cohort studies and 239 in one randomized controlled trial.) 

They compared the endometrioma recurrence rates in patients who used oral contraceptives during the entire study follow-up period. These were “always” users. There were also “ever” users, which were patients who used oral contraceptives at some points but not during the entire time. “Never” users were patients who didn’t use oral contraceptives post excision during the study follow-up period.

Always vs never users: “A recurrent endometrioma was identified in 33 of 423 (8%) “always” OC users and in 117 of 341 (34%) women [“never” users] who underwent expectant management (pooled odds ratio 0.12; 95% confidence interval 0.05–0.29).”

Always vs ever users: “In order to determine whether duration of OC use had an effect on the study outcome, we considered the three cohort studies and compared the endometrioma recurrence rate observed in the 275 “always” users and in the 179 “ever” users. In the former group, 16 endometriotic cysts were detected (6%; 95% CI 4–9%), compared with 48 in the latter (27%; 95% CI 21–34%).”

This study found that “Postoperative OC use dramatically decreased the risk of ovarian endometrioma recurrence, especially in women who used OCs regularly and for prolonged periods.”

Discussion about this study

The study by Vercellini et al above looked specifically at oral contraceptives taken for at least 12 months post excision of an endometrioma. (In fact, the follow up periods in the 4 studies reviewed were 24-35 months.)

While the “always” and “ever” oral contraceptive users had an overall lower endometrioma recurrence rate than “never” users, some of the patients on oral contraceptives still had recurring endometriomas. Taking oral contraceptives post excision is not a guarantee that you won’t have endometrioma recurrence.

Summary of different studies

I’ve linked several studies on endometrioma recurrence below that you can read. Here’s a summary of what I understood from them. (Remember, I’m not a doctor or a researcher, so make sure to do your own research).

Multiple studies suggest that long term use (2-3 years) of hormones after excision reduces the rate of endometrioma recurrence. However, a few studies also suggest that while using hormones, the rates are reduced but once patients stop them, the recurrence rate rises rapidly. Since it appears that the potential benefit is while the patient is taking hormones, this highlights the need to find one that has fewer side effects and is tolerable for you long term.

What’s the best hormone?

A systematic review by Wattanayingcharoenchai et al (4) looking at six RCTs (675 patients) and 16 cohorts (3089 patients) did a network meta‐analysis of the RCTs involving expectant management (this is when patients don’t use hormones), cyclic OC, continuous OC, GnRHa (agonist) and GnRHa + LNG‐IUS (levonorgestrel-releasing intrauterine system), showed that all hormonal regimens had a nonsignificant lower risk of endometrioma recurrence compared with expectant management.

In that same study, a network meta-analysis of the cohorts involving expectant management, cyclic OC, continuous OC, GnRHa, Dienogest, LNG‐IUS, GnRHa + OC, and GnRHa + LNG‐IUS indicated that cyclic OC, continuous OC, Dienogest, LNG‐IUS, and GnRHa + OC and had a significantly lower risk of endometrioma recurrence than expectant management.

There have been several studies done on oral contraceptives, so keep in mind that if you are hoping to lower your endometrioma recurrence, you don’t have to take GnRh drugs (which are very serious with a high side effect profile), but you can use OCs or progestins instead which have lower side effects. In studies comparing continuous vs cyclical use of OC, the continuous users tend to have lower rates of recurrence than the cyclical users (although in some studies, the recurrence rate between continuous vs cyclic users wasn’t statistically significant).

Studies suggest that hormones that can suppress ovulation are best at reducing the risk of potential endometrioma recurrence. The levonorgestrel-releasing IUD doesn’t reliably reduce ovulation, and one very small study on long-term use found it wasn’t effective at lowering endometrioma recurrence, with endometrioma recurrence at 30 months having no significant difference between the 2 groups. In the IUD group, 25% (10 of 40) had recurrence vs in the control group, 37.5% (15 of 40) had recurrence. (3)

Does the type of progestin matter in oral contraceptives?

A small study by Cucinella et al. on 168 patients with 24 months follow up compared endometrioma recurrence rates in 4 groups (1 group of expectant management, and 3 using oral contraceptives each with a different progestins: desogestrel, gestodene, and dienogest) and didn’t find significant differences between them, although they did find that recurrence in these 3 groups was statistically lower than in the control group not using hormones. 

Will taking hormones post excision definitely prevent endometrioma recurrence?

No. You can still have endometrioma recurrence while taking hormones, as evidenced both by patient experience and over a dozen studies looking at patients taking hormones. 

One RCT with 239 patients by Seracchioli et al.(6) comparing recurrence rate in patients taking continuous OC, cyclic OC, or no OC for at least 24 months found that the average diameter of the recurrent endometrioma was smaller for those who used the OC continuously or cyclically and their endometriomas grew at a slower rate, compared to those who didn’t use OC.

If I don’t take hormones post surgery, will I definitely have endometrioma recurrence?

No. As evidenced both by patient experience and over a dozen studies looking at patients not taking hormones, recurrence rates for excision are not even close to 100%. 

The study by Veth et al (7) specifically tried to answer the question of what is the recurrence rate for surgically treated endometrioma without postoperative hormonal treatment. It looked at 12 RCTs, 11 prospective cohort studies, and 32 retrospective studies, where surgical treatment of the endometrioma included cystectomy, vaporization by laser or plasma energy, or ablation by electrocoagulation.

In the meta-analyses, the recurrence rates were:

• 4% for the 3-month follow-up period (based on 125 patients from 4 studies) 
• 14% for the 6-month follow up period (229 patients from 5 studies).
• 17%  for the 12-month follow-up period (729 patients from 13 studies). 
• 27% for the 24-month follow-up period (313 patients from 5 studies).

While we can’t ever know the exact recurrence rate for patients (with or without hormone use), we know that recurrence is not guaranteed if you don’t take hormones, so you shouldn’t be scared into taking them by fear that you will definitely have recurrence if you don’t take them.

What influences the rate of recurrence in a study?

The sample size, the length of follow-up, the definition of recurrence, the surgeon’s skills, the completeness of the surgery, the surgical technique used, the actual individual’s bodies in the studies. All studies have limitations and bias, and some studies have found conflicting results.

Do these studies apply to superficial and deep endometriosis?

No, endometriosis is a heterogeneous disease, and endometriomas can be responsive to ovarian hormones. Studies on recurrence or progression are often done on endometriomas because they can be seen on ultrasound. The results of these studies on endometriomas cannot be applied to other types of endometriosis.