Endometriosis: Management of ovarian endometriomas

INTRODUCTION — An ovarian endometrioma is a cystic mass arising from ectopic endometrial tissue within the ovary. It contains thick, brown, tar-like fluid, which may be referred to as a "chocolate cyst." Endometriomas are often densely adherent to surrounding structures, such as the peritoneum, fallopian tubes, uterus, and bowel. This topic will review management of ovarian endometriomas.

Information on adnexal masses and the clinical diagnosis and management of endometriosis is discussed separately.

●(See "Approach to the patient with an adnexal mass".)

●(See "Endometriosis in adults: Pathogenesis, epidemiology, and clinical impact".)

In this topic, when discussing study results, we will use the terms "women" or "patients" as they are used in the studies presented. However, we encourage the reader to consider the specific counseling and treatment needs of transgender and gender diverse individuals.

BASELINE EVALUATION — The baseline evaluation for individuals with suspected endometriomas includes:

●Assessment of symptoms

●Pelvic imaging, typically with transvaginal ultrasound

●Assessment of the risk of malignancy

●Evaluation of the patient's ovarian reserve

●Planning for future fertility

Assess symptoms — Endometriomas can be asymptomatic or cause symptoms of pain, dyspareunia, and/or mass effect. Endometriomas causing bothersome symptoms that interfere with routine function are removed for symptom relief [1-4].

Perform imaging — Imaging studies are performed to confirm a likely endometrioma, exclude findings suggestive of malignancy, and assess for change over time. While definitive diagnosis of an endometrioma requires histologic evaluation of a surgical specimen, imaging findings have high sensitivity and specificity for detecting an endometrioma. (See "Endometriosis: Clinical features, evaluation, and diagnosis", section on 'Imaging'.)

●Ultrasound imaging – Ultrasound is typically the first-line imaging study for evaluating an adnexal mass (image 1A-B) [5]; the sensitivity and specificity are greater than 90 percent for diagnosing an endometrioma [6,7]. Individuals with an indeterminate adnexal mass may benefit from repeat interval imaging (eg, hemorrhagic cyst) or magnetic resonance imaging (MRI) for further delineation (eg, concern for malignancy) [7]. (See "Approach to the patient with an adnexal mass", section on 'Diagnosis'.)

Findings suggestive of an endometrioma include an avascular, thick-walled cystic mass that contains material with a homogenous low-level echo pattern (ie, ground-glass appearance) (image 1A-C) [5,8]. The lesion may be uni- or multilocular; multilocular lesions can have varying levels of echogenicity. Septations should be smooth and there should be no solid elements. Cyst size is measured in three orthogonal planes [9]. Serial images can assess subsequent changes in size or appearance.

●Magnetic resonance imaging (MRI) – MRI can be useful if the initial ultrasound findings are indeterminate for endometrioma or to assist with preoperative planning [6,7,10]. The number of adnexal lesions that remains with an indeterminate diagnosis drops from 20 to 25 percent with ultrasound to 5 to 7 percent with MRI [11-17].

Assess risk for malignancy — While the overall risk of malignancy within an endometrioma is low, typically less than 0.8 percent, risk of malignancy is increased with larger lesions (>9 cm) and increasing patient age (>45 years) [18]. Endometriosis of the ovary is also associated with a small increased risk of transformation to ovarian cancer; the most common histologies are clear cell and endometrioid [19-21]. For these reasons, endometriomas are removed if they have an atypical appearance on imaging studies, other concerning features (eg, enlarging size, nodularity), or occur in patients of older age [22]. (See "Endometriosis in adults: Pathogenesis, epidemiology, and clinical impact", section on 'Ovarian cancer risk'.)

Serum CA 125 level is generally not helpful in assessing for possible malignancy because the level may be increased with benign endometriomas [23,24]. However, CA 125 levels over 200 units/mL has been used as a criterion for specialist referral and evaluation for possible malignancy [25]. (See "Adnexal mass: Role of serum biomarkers in diagnosing epithelial carcinoma of the ovary, fallopian tube, or peritoneum" and "Adnexal mass: Role of serum biomarkers in diagnosing epithelial carcinoma of the ovary, fallopian tube, or peritoneum", section on 'Biomarkers'.)

Assess fertility and desire for pregnancy — Excision of endometriomas improves spontaneous pregnancy rates in subfertile individuals but has no impact when advanced reproductive technologies such as in vitro fertilization (IVF) are employed [26]. Endometrioma resection has not been shown to improve IVF/intracytoplasmic sperm injection outcomes and therefore is not advised for this indication [4,27-29]. Patients planning IVF or intracytoplasmic sperm injection should consider endometrioma resection only if they are having bothersome symptoms (eg, pain or mass), to exclude malignancy, or if the size and/or position of the endometrioma would preclude follicle aspiration during a planned future IVF cycle [4]. (See "Endometriosis: Treatment of infertility in females".)

●In one study of women with subfertility and endometriomas, excision of the endometrioma was associated with an increased spontaneous pregnancy rate compared with women who had cyst wall ablation only [26].

●Conception and pregnancy rates are not improved when endometriomas are treated with hormonal treatments such as danazol or gonadotropin-releasing hormone (GnRH) agonists, although cyst size may be reduced [30,31]. (See 'Active surveillance' below.)

CONSIDER IMPORTANCE OF OVARIAN RESERVE — Ovarian reserve, as measured by serum anti-müllerian hormone (AMH), is decreased in patients with endometriomas >3 cm in diameter and further decreased if the endometrioma is surgically removed [32]. While AMH level does not predict the probability of natural conception, it does predict live birth following in vitro fertilization (IVF). Therefore, the decision to proceed with ovarian surgery requires a careful discussion with the patient regarding the impact on ovarian function. AMH levels are only one marker of ovarian reserve and must be assessed within the entire clinical context; more information on ovarian reserve is presented elsewhere. (See "Female infertility: Evaluation", section on 'Assessment of ovarian reserve'.)

●Impact of endometrioma – Endometrioma has been associated with reduced AMH levels and greater AMH decline over time [33,34]. In a study comparing AMH levels in 40 patients with endometrioma >3 cm with 40 age-matched control individuals without endometriomas, those with endometriomas had lower median AMH levels at study recruitment (2.83 versus 4.42 ng/mL) and greater AMH decline over six months (26 versus 7 percent) [34]. Although the endometrioma may reduce AMH levels and the number of follicles recruited in the ovary by exogenous follicle-stimulating hormone (FSH) stimulation, endometriomas do not appear to negatively impact pregnancy or live birth rates after IVF [35-37]. However, the reduction in follicle count may negatively impact individuals undergoing IVF with the goal of preserving oocytes or embryos for possible future use.  

●Impact of endometrioma surgery (cystectomy) – Ovarian surgery to remove the endometrioma (ie, cystectomy) is associated with reduced ovarian reserve as assessed by AMH levels but not by antral follicle count (AFC) [38-40]. It is unclear if AMH falls because of surgical trauma to the ovary or removal of normal ovarian tissue and follicles.

•Cystectomy and AMH – A meta-analysis of 14 prospective studies comparing pre- and postoperative AMH and AFC levels in 650 females who underwent endometrioma resection (cystectomy) reported reductions in weighted mean AMH of 44, 35, and 54 percent at early (one to six week), intermediate (two to six months), and late (nine to eighteen months) postoperative time intervals, respectively [38]. By contrast, weighted mean AFC levels were similar pre- and postoperatively. Other studies have reported bilateral cystectomy for endometriomas may result in a greater reduction in AMH levels than unilateral ovarian cystectomy [41,42]. While AMH does not predict the probability of natural conception, it does predict the likelihood of live birth following IVF [38].

•Repeat surgeries and AMH – A prospective study that assessed ovarian function reported a greater loss of ovarian tissue and antral follicles in the females undergoing repeat surgery compared with those undergoing primary endometrioma resection [43]. The authors cautioned against repeat surgical intervention for endometriomas.

TREATMENT GOALS AND OPTIONS — Treatment options include active surveillance with serial imaging and surgical excision (cystectomy or oophorectomy). Medical therapy and cyst sclerotherapy are not advised. (See 'Lack of benefit' below.)

Select treatment approach — The goals of endometrioma treatment are to relieve symptoms (eg, pain or mass), exclude malignancy, and improve subfertility (if assisted reproductive technology is not being pursued), all while preserving ovarian function. (See 'Baseline evaluation' above.)

The main treatment options include active surveillance with serial imaging or surgical removal with cystectomy or oophorectomy (algorithm 1). The relative priority of each of the treatment goals above informs treatment selection.

●Active surveillance – In the absence of symptoms or concerning findings, observation with serial imaging is preferred as it avoids the risks of surgery and the potential negative impact of surgery on ovarian reserve. (See 'Active surveillance' below.)

●Surgical treatment – When surgery is elected, the goals are to relieve symptoms (eg, pain or mass), exclude malignancy, and improve subfertility with minimizing negative impact on ovarian function. Surgical options include cystectomy (ie, removal of the endometrioma only with preservation of the ovary) or oophorectomy (ie, removal of the ovary with the intact cyst within it). When cost is included in the decision-making process, one group reported that salpingo-oophorectomy may be preferred to cystectomy [44]. (See 'Surgery' below.)

Sclerotherapy and medication management are not advised as they are ineffective. (See 'Lack of benefit' below.)

Active surveillance — Active surveillance employs serial ultrasounds to confirm findings consistent with an endometrioma and cyst stability (algorithm 1).

●Patient selection, benefits, and risks – Active surveillance with serial imaging is appropriate for most patients and includes those who are asymptomatic, who have small lesions (<5 cm), are at low risk for malignancy based on clinical factors and imaging findings, and who prioritize their existing ovarian function [3]. (See 'Assess risk for malignancy' above and 'Assess fertility and desire for pregnancy' above.)

•Benefits – Benefits of observation include preserved ovarian function and avoidance of surgical risk [45-47]. Observation over time also allows other benign ovarian cysts that could be confused for an endometrioma, such as hemorrhagic cysts, to regress.

•Risks – The risks of observation include lack of histologic diagnosis, inability to exclude malignancy, and potential for disease progression.

●Approach – For endometriomas that are being observed, a typical management plan involves physical examination and ultrasound every six months for one to two years, followed by annual examination and ultrasound if the adnexal mass has remained unchanged in size and clinical characteristics. Patients can be managed for many years using this conservative approach. Benefits include maintenance of ovarian reserve and avoidance of surgery.

●Indications for change in approach – Onset of new symptoms or increasing cyst volume (the authors use cyst size >5 cm) or complexity on imaging should prompt closer follow-up (ie, repeat pelvic ultrasound in 3 rather than 6 or 12 months). Two consecutive scans demonstrating clinically meaningful increased cyst volume or change in complexity of the cyst, or development of significant symptoms, should prompt surgical intervention. (See "Approach to the patient with an adnexal mass", section on 'When to stop surveillance or proceed with surgery'.)

●Adjunct medical therapy – Hormonal therapy generally has no significant impact on endometrioma volume and is not indicated specifically for management of endometriomas. However, dienogest 2 mg per day has been associated with modest decreases in endometrioma cyst volume [48-50]. Ovulation suppression with hormonal therapy is beneficial in managing dysmenorrhea and may be useful in managing chronic pain symptoms associated with endometriosis [48,49].

Surgery — Surgical resection with either cystectomy or oophorectomy provides a definitive diagnosis, symptom relief, and exclusion of malignancy (image 2 and algorithm 1). Risks of surgical resection include potential decreased ovarian reserve after resection and standard surgical risks [45,51,52]. (See "Oophorectomy and ovarian cystectomy", section on 'Oophorectomy versus cystectomy'.)

Cystectomy (conservative surgery) — Cystectomy involves removal of the endometrioma cyst while leaving the remainder of the normal ovary intact.

Our approach — For those with known endometriosis, a symptomatic endometrioma, and/or an expanding suspected endometrioma, we suggest cystectomy, preferably by the laparoscopic route, rather than oophorectomy (algorithm 1). We inform patients that  conversion to laparotomy may be necessary in approximately 5 percent of attempted laparoscopic cystectomies for endometriomas, which is higher compared with other benign ovarian lesions [53].

●Cystectomy removes the endometrioma and provides an opportunity to resect other sites of endometriosis but leaves the normal ovary intact [22].

●We perform pelvic washing and frozen section evaluation in cases with suspicious or unusual morphology, either by ultrasound or direct visualization at the time of surgery.

●After surgical resection, we recommend long-term treatment with an estrogen-progestin contraceptive to prevent endometrioma recurrence [54]. (See 'Postoperative management' below.)

Cystectomy versus aspiration, fenestration, or sclerotherapy — Cystectomy, preferably by laparoscopy, is preferred to other interventions for the treatment of pelvic pain or infertility because it is associated with a lower risk of endometrioma recurrence [4,26].

●Aspiration – Cyst aspiration alone is ineffective with reported recurrence rates of 80 to 100 percent at six months of follow-up [55-58]. (See "Oophorectomy and ovarian cystectomy", section on 'Aspiration and fenestration versus cystectomy'.)

●Fenestration and ablation – Fenestration (removal of part of the cyst wall) and ablation (coagulation or laser vaporization of the inner side of the wall) is less effective than cystectomy, both in terms of improving fertility and reducing pain, but may have less impact on ovarian reserve [26,59]. (See "Oophorectomy and ovarian cystectomy", section on 'Aspiration and fenestration versus cystectomy'.)

●Cyst sclerotherapy has also been attempted as a less-invasive alternative to cystectomy but has an unacceptably high recurrence rate without demonstrated benefit [60]. However, cyst sclerotherapy may be useful to reduce cyst size with the goal of improving access to follicles for aspiration during an IVF cycle [61]. (See 'Cyst sclerotherapy' below.)

Cystectomy technique — Surgical issues to be considered at the time of endometrioma removal include the method of cyst removal, choice of hemostatic agent, and the extent of adjacent disease.

●Method of cyst removal – Stripping the cyst wall instead of performing a circular excision around the cyst limits the number of normal ovarian follicles removed with the specimen [62]. A histologic analysis of endometriomas showed endometriosis of the inner cyst wall rarely penetrates more than 1.5 mm into the cyst capsule [63].

●Hemostatic technique – Choice of hemostatic technique used on the ovary appears to impact postoperative anti-müllerian hormone (AMH) levels [64-68]. Two different meta-analyses reported hemostatic sealants and suture caused less reduction in AMH levels compared with bipolar electrosurgery [69,70]. We agree with the authors' suggestion to limit the use of bipolar electrocoagulation on the ovary. (See "Instruments and devices used in laparoscopic surgery", section on 'Electrosurgery'.)

Use of oxidized regenerated cellulose can reduce surgical site bleeding and has been associated with reduced risk of cyst recurrence when used with both cyst drainage and cystectomy. In a trial including 200 patients with endometriomas that compared cystectomy and cyst drainage, each with and without application of oxidized cellulose, cyst recurrence rates were lower for both cellulose-treated groups over two years of follow-up [71]. AMH levels dropped in both cystectomy groups but remained unchanged in the group that underwent cyst drainage with cellulose insertion.

●Adjacent disease and/or adhesions – In our experience, endometrioma removal is often more difficult than the removal of other benign ovarian cysts because the contents of the endometrioma can chronically leak into the peritoneal cavity. This leakage causes dense scarring to structures adjacent to the cyst, making complete cystectomy more challenging. As cystectomy of endometriomas can be quite difficult, we discuss the potential need for oophorectomy with all individuals planning surgery.

●Management of other benign cysts – Many patients with endometriomas also have other benign ovarian cysts, such as hemorrhagic corpus luteum cysts or follicular cysts. While these adjacent cysts often increase the difficulty of endometrioma removal, they are left in situ when possible in an effort to retain as much normal ovarian tissue as possible.

Oophorectomy with or without hysterectomy (definitive surgery) — Oophorectomy involves removal of the ovary with the cyst intact and provides definitive surgical treatment. However, oophorectomy results in loss of ovarian function and bilateral oophorectomy in those under age 50 appears to increase the risks of all-cause mortality and cardiovascular disease. Decision to remove an ovary involves careful discussion on the risks of endometrioma recurrence and symptoms compared with risks and sequelae of loss of ovarian hormones (algorithm 1). At least one study has reported that salpingo-oophorectomy is more cost-effective than cystectomy for managing ovarian endometrioma in premenopausal patients [44]. (See "Elective oophorectomy or ovarian conservation at the time of hysterectomy", section on 'Consequences of elective oophorectomy'.)

●Indications – Oophorectomy is mainly performed in patients who have recurrent cysts, have completed childbearing, are postmenopausal, or who have concerns for malignancy [22]. Unilateral oophorectomy resolves symptoms and reduces the risk of endometrioma recurrence. However, endometriomas or other cysts can still form in the contralateral ovary and, rarely, a retained ovarian remnant can cause pain symptoms. (See "Oophorectomy and ovarian cystectomy", section on 'Ovarian remnant syndrome'.)

●Impact on ovarian hormone production

•Unilateral oophorectomy – The impact of unilateral oophorectomy on ovarian hormone production is unclear. Most studies that assess hormone production from the remaining ovary have looked at patients undergoing hysterectomy with and without unilateral oophorectomy. In studies of women having hysterectomy, the time interval to cessation of ovarian function is shorter for those who have unilateral oophorectomy in addition to hysterectomy, which raises concern that oophorectomy alone may reduce residual ovarian function [72-75]. Premature loss of ovarian function is associated with increased risk for cognitive impairment and cardiovascular events [75-77]. (See "Elective oophorectomy or ovarian conservation at the time of hysterectomy", section on 'Consequences of elective oophorectomy'.)

•Bilateral oophorectomy – Bilateral oophorectomy results in complete loss of ovarian function. Thus, this procedure is typically reserved for patients who have debilitating symptoms, have failed other therapies, and have completed childbearing [3]. Bilateral oophorectomy can be performed with or without concomitant hysterectomy and/or bilateral salpingectomy. (See "Elective oophorectomy or ovarian conservation at the time of hysterectomy".)

●Removal of entire adnexa (en bloc dissection) – If the patient has extensive unilateral pain and/or scarring around the ovary containing the endometrioma, the patient may benefit from removal of the entire adnexa (ie, en bloc dissection of the ovary, fallopian tube, and surrounding tissue). This dissection may necessitate opening the retroperitoneum, identifying and isolating the ureter, and ligating the infundibulopelvic ligament near the pelvic brim to avoid operating near the diseased tissue. This approach reduces the risk of retained ovarian tissue that could cause further symptoms. (See "Ovarian remnant syndrome".)

Option for prophylactic salpingectomy — Individuals who elect surgery with either ovarian cystectomy or oophorectomy have the option of concurrent salpingectomy (removal of the fallopian tubes) to reduce the risk of epithelial ovarian, fallopian tube, and peritoneal cancers. The balance of risks and benefits for this additional surgery depend on the patient's baseline risk of these cancers. Salpingectomy for cancer risk reduction is presented in detail in related content.

●(See "Risk-reducing salpingo-oophorectomy in patients at high risk of epithelial ovarian and fallopian tube cancer".)

●(See "Opportunistic salpingectomy for ovarian, fallopian tube, and peritoneal carcinoma risk reduction".)

Postoperative management

Goals of treatment — The use of postoperative medical therapy depends on the indication(s) for surgery and the patient's preferences regarding immediate attempt at pregnancy, use of medication, potential side effects of medication, and risk of cyst recurrence.

●Reduction of endometriosis-related pain recurrence – We, and other societies, advise postoperative medical suppressive therapy for most individuals treated surgically for endometriosis-related pain symptoms [3,4,22]. Individuals who desire immediate attempt of pregnancy are an exception. Discussion of treatment options and supporting data are reviewed separately. (See "Endometriosis: Surgical management of pelvic pain", section on 'Postoperative care'.)

●Reduction of endometrioma recurrence – Postoperative medical treatment appears to reduce the risk of endometrioma recurrence if maintained for at least a year; the optimal drug regimen is not known and the available data are mixed [78,79]. Although the supporting data are of low quality, long-term suppression with combined estrogen-progestin contraceptives appears to be helpful and is of low overall risk. (See "Endometriosis: Treatment of pelvic pain", section on 'Estrogen-progestin contraceptives'.)

•A 2022 network meta-analysis comparing medical treatment for a mean duration of at least 12 months with expectant management reported combined therapy with a gonadotropin-releasing hormone (GnRH) agonist and hormonal suppression was associated with lower risk of endometrioma recurrence compared with GnRH agonist alone or expectant management [79]. Hormonal suppression included oral contraceptive (OC) pills (multiple formulations), dienogest, and levonorgestrel intrauterine devices (LNG IUDs). The risk of endometrioma recurrence was similar for treatment with GnRH agonist alone and expectant management (odds ratio 0.47, 95% CI 0.12-1.89). Shorter duration of treatment (three to six months) was not associated with reduced recurrence risk.

•A 2021 network meta-analysis of six trials and 16 cohort studies reported a nonsignificant trend toward lower endometrioma recurrence rates with postoperative use of hormonal suppression, including OCs (continuous and cyclic), dienogest, LNG IUDs, and GnRH agonist therapy, compared with expectant management [78].

Options for medical therapy — Options for treatment of endometriosis-related pain include estrogen-progestin contraceptives, progestin-only therapies, GnRH agonists and antagonists, and LNG IUDs. If postoperative medical treatment is elected, estrogen-progestin contraceptives are often used because of general tolerability, availability, and ease of use in addition to data supporting reduced endometrioma recurrence rates with long-term (one year or greater) use. (See "Endometriosis: Treatment of pelvic pain", section on 'Medical treatment options'.)

Likely helpful

●Oral contraceptives (OCs) – Postoperative treatment with either a cyclic or continuous estrogen-progestin OC regimen is reasonable as treatment has been associated with reduced risk of endometrioma recurrence and reduction of endometriosis-related symptoms [54,79-82]. Continuous-dose OC regimens may provide additional benefit over cyclic ones [83]. Combined therapy with estrogen and progestin is preferred to progestin treatment alone; a study of endometrioma cells reported that cell growth was suppressed more by combination therapy with ethinyl estradiol and progestin than by progestins alone [84]. Estrogen-progestin contraceptive vaginal rings and patches have also been associated with reduction in endometriosis-related symptoms, but their impact on postoperative endometrioma recurrence has not been established [85].

•(See "Endometriosis: Surgical management of pelvic pain", section on 'Postoperative medical therapy'.)

•(See "Endometriosis: Treatment of pelvic pain", section on 'Estrogen-progestin contraceptives'.)

●Dienogest – Studies have reported postoperative dienogest reduced risk of endometrioma recurrence, was associated with resolution of recurrent cysts, and preserved AMH levels [86-88]. If used, treatment of six months or greater is advised as shorter duration of treatment has been associated with endometrioma recurrence risk similar to that of expectant management [78].

Unclear benefit

●GnRH agonists and antagonists – Both GnRH agonist and antagonist therapy can be used for postoperative suppressive therapy for endometriosis and its related symptoms [89-92]; impact on endometrioma recurrence is less clear [78]. (See "Endometriosis: Treatment of pelvic pain", section on 'Gonadotropin-releasing hormone (GnRH) analogs'.)

●Levonorgestrel intrauterine devices (LNG IUDs) – While studies report reduced rates of dysmenorrhea in patients treated with LNG IUDs after surgical removal of endometriomas, the impact of LNG IUDs on endometrioma recurrence is less clear because of small study size, short duration of follow-up, and lack of placebo comparator [93-95]. Until further data are available from larger trials, we do not advise LNG IUD insertion for prevention of endometrioma recurrence and instead offer patients treatment with OCs as described in the first bullet. (See "Endometriosis: Treatment of pelvic pain", section on 'Alternate progestin treatment options'.)

RISK OF ENDOMETRIOMA RECURRENCE

Incidence — Approximately 25 percent of patients who undergo surgical endometrioma removal will experience endometrioma recurrence [96-98]. In a study of 289 women who had undergone endometrioma resection, risk factors for endometrioma recurrence included removal of a cyst >8 cm, younger age (<25 years), and preoperative cyst rupture [96].

Repeat imaging is performed to reasonably exclude malignancy when recurrent endometrioma is suspected. (See "Approach to the patient with an adnexal mass", section on 'Patients at increased risk of malignancy'.)

Concerns for repeat cystectomy — Repeat cystectomy to remove a recurrent endometrioma may be more damaging to the ovary than initial cystectomy, although supporting data are limited to very small observational studies.

●One study of 11 women undergoing endometrioma cystectomy reported that the cyst wall specimen was thicker and contained more normal ovarian tissue in the recurrent endometrioma group as compared with the primary endometrioma resection group [43]. The recurrent endometrioma resection group also had a reduced antral follicle count (AFC) and ovarian volume on follow-up ultrasound study.

●In another study that compared 18 women undergoing a second unilateral endometrioma resection with 18 women who underwent a primary resection only, the repeat resection group had decreased anti-müllerian hormone (AMH) levels, higher basal follicle-stimulating hormone (FSH) levels, and lower AFCs compared with the primary resection group [99]. Of note, the values for AMH, FSH, and AFC were not different between the groups after the primary surgery, which indicates the second surgery had an increased negative impact on ovarian reserve.

LACK OF BENEFIT — Medication management and sclerotherapy are not advised as they do not resolve endometriomas or treat associated symptoms.

Medical therapy — While medical therapy is an effective treatment for pelvic pain caused by endometriosis, until recently it was thought that it has no benefits over observation for management of endometriomas [1,3,100]. However, three small observational studies assessing the impact of dienogest 2 mg daily reported a significant reduction in endometrioma volume (approximately 40 percent at six months and as much as 76 percent at 12 months) in addition to reductions in pelvic pain scores [50,101,102]. Although long-term data are lacking, dienogest may be considered for primary medical management in patients who prioritize avoiding surgery or for postoperative therapy to prevent recurrence. (See "Endometriosis: Treatment of pelvic pain".)

Cyst sclerotherapy — Cyst sclerotherapy has also been attempted as a less-invasive alternative to cystectomy. However, the endometrioma recurrence rate after sclerotherapy has been reported to be as high as 63 percent, without an improvement in clinical pregnancy rate when compared with traditional cystectomy or no treatment [60]. Sclerotherapy consists of injecting a sclerosing agent (ethanol, tetracycline, or methotrexate) into the cyst cavity and is thought to disrupt the cyst epithelial lining, which results in inflammation, fibrosis, and, ultimately, obliteration of the cyst. Comparing sclerotherapy with surgical resection have reported higher anti-müllerian hormone (AMH) levels following sclerotherapy but similar clinical pregnancy rates [60,103].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Endometriosis".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Beyond the Basics topic (see "Patient education: Endometriosis (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Baseline evaluation – The baseline evaluation for individuals with suspected endometriomas includes imaging, typically with transvaginal pelvic ultrasound; assessment of risk of malignancy and presence of symptoms; and consideration of the patient's ovarian reserve and plan for future fertility. (See 'Baseline evaluation' above.)

●Importance of ovarian reserve – Endometriomas themselves do not appear to diminish ovarian reserve but surgery to remove them is associated with reduced ovarian reserve as measured by anti-müllerian hormone (AMH) levels. While AMH level does not predict the probability of natural conception, it does predict live birth following in vitro fertilization (IVF). Therefore, the decision to proceed with ovarian surgery requires a careful discussion with the patient regarding the impact on ovarian function and plans for future fertility. (See 'Consider importance of ovarian reserve' above.)

●Treatment options – The main treatment options include active surveillance with serial imaging or surgical removal with cystectomy or oophorectomy (algorithm 1).

•Active surveillance – Active surveillance involves serial imaging to confirm findings consistent with an endometrioma and cyst stability. This approach preserves ovarian function and avoids surgical risk but cannot exclude malignancy. (See 'Cystectomy (conservative surgery)' above.)

•Surgical resection – Surgical resection with either cystectomy or oophorectomy provides a definitive diagnosis, relief of symptoms, and exclusion of malignancy. Risks of surgical resection include standard surgical risks and likely decreased ovarian reserve after resection (see 'Surgery' above). Some evidence suggests that surgical cyst drainage with placement of Surgicel may preserve ovarian function with recurrence rates similar to cystectomy.

•Treatments lacking benefit – Currently available medical therapy does not treat endometriomas and cyst sclerotherapy is associated with a high risk of recurrence. (See 'Lack of benefit' above.)

●Select treatment approach – Management options include active surveillance with serial imaging or surgical resection (algorithm 1). (See 'Select treatment approach' above.)

•Asymptomatic endometrioma – For individuals with asymptomatic cysts that have the imaging-based characteristics of an endometrioma and no other clinical risk factors for ovarian cancer, we suggest active surveillance rather than surgical excision (Grade 2C). We prefer active surveillance for those with a known diagnosis of endometriosis as excision may damage ovarian reserve. However, patients with symptoms related to the cyst (eg, pain), imaging findings suggestive of malignancy, or risk factors for ovarian cancer proceed with surgical excision of the lesion for histology diagnosis and treatment of pain. (See 'Active surveillance' above.)

•Endometrioma with symptoms – For patients with endometrioma-related symptoms (eg, pain, mass effect) who elect surgery with ovary conservation, we recommend cystectomy rather than fenestration and ablation (Grade 1B). Fenestration and ablation are less effective than cystectomy in reducing pain and improving fertility. We perform laparoscopic cystectomy with the stripping technique to preserve normal ovarian tissue. Aspiration is ineffective (see 'Cystectomy (conservative surgery)' above). Cyst drainage with Surgicel placement is a promising technique to preserve ovarian function with recurrence rates similar to cystectomy.

•Recurrent symptomatic endometrioma – Oophorectomy is reserved for patients with recurrent symptomatic endometriomas or for cysts with imaging findings concerning for malignancy. Bilateral oophorectomy, with or without concomitant hysterectomy, is reserved for individuals who have debilitating symptoms, have failed other therapies, and/or have completed childbearing. (See 'Oophorectomy with or without hysterectomy (definitive surgery)' above.)

●Postoperative treatment – For premenopausal individuals who undergo surgical resection of endometrioma, we suggest postoperative use of estrogen-progestin oral contraceptive (OC) therapy rather than observation to reduce the risk of endometrioma recurrence (Grade 2B). Oral estrogen-progestin treatment has been associated with reduction of endometrioma recurrence and endometriosis-related symptoms. We typically prescribe combined OCs as efficacy of estrogen-progestin vaginal contraceptive rings and patches for endometrioma treatment has not been established. Continuous-dose regimens may provide additional benefit over cyclic therapy but both are reasonable; selection depends on patient preference. (See 'Postoperative management' above.)

●Risks of endometrioma recurrence – Approximately 25 percent of women who undergo surgical endometrioma removal will experience endometrioma recurrence. Repeat cystectomy to remove a recurrent endometrioma may be more damaging to the ovary than initial cystectomy. (See 'Risk of endometrioma recurrence' above.)