Endometriosis and atherosclerosis: what we already know and what we have yet to discover

Growing evidence that endometriosis is a systemic disease

The pathophysiology of endometriosis remains unclear. Retrograde menstruation could be a phenomenon that initiates the process, but it may not explain the entire pathophysiology of endometriosis. Current evidence suggests that endometriosis is a type of chronic inflammatory disease. Many conditions that affect the vascular endothelium, including atherosclerosis, cardiovascular disease and pre-eclampsia, have been shown to be associated with endometriosis. Evidence to date suggests a complex interaction in endometriosis between angiogenesis, hormones and immunological changes stemming from chronic inflammation, with the inflammatory cells releasing cytokines and chemokines including tumour necrosis factor-α (TNF-α). Indeed, TNF-α is considered to be one of the possible markers of endometriosis in the blood, endometrium or menstrual blood. We emphasize the importance of pursuing research for novel and safer anti-inflammatory and immunomodulatory drugs that can be used by patients with endometriosis on a long-term basis.

Gene associations of lipid traits, lipid-lowering drug-target genes and endometriosis

RESEARCH QUESTION

Does the observed correlation between dyslipidaemia and endometriosis indicate a bidirectional causal association?

DESIGN

Bidirectional Mendelian randomization was used to investigate the causal association between lipid traits and endometriosis. Drug-target Mendelian randomization was used to explore potential drug-target genes for managing endometriosis. In cases where lipid-mediated effects via specific drug targets were significant, aggregate analyses, such as summary-data-based Mendelian randomization and colocalization methods, were introduced to validate the outcomes. Mediation analyses supplemented these evaluations.

RESULTS

The bidirectional Mendelian randomization results suggested that genetically predicted triglyceride (OR 1.15, 95% CI 1.08-1.23), high-density lipoprotein cholesterol (OR 0.87, 95% CI 0.81-0.94), low-density lipoprotein cholesterol (OR 1.20, 95% CI 1.06-1.34) and apolipoprotein A (OR 0.90, 95% CI 0.83-0.96) concentrations were causally associated with endometriosis. Reverse Mendelian randomization results revealed that genetically proxied endometriosis was causally associated with triglyceride concentration (OR 1.02, 95% CI 1.01-1.02). In drug-target Mendelian randomization, genetic mimicry in proprotein convertase subtilisin/kexin type 9 (PCSK9) (OR 1.40, 95% CI 1.13-1.72), apolipoprotein B (APOB) (OR 1.49, 95% CI 1.21-1.86) and angiopoietin-related protein 3 (ANGPTL3) (OR 1.57, 95% CI 1.14-2.16) was significantly associated with the risk of endometriosis stages 1-2.

CONCLUSION

There is a potential bidirectional causal association between endometriosis and dyslipidaemia. Genetic mimicry of PCSK9, APOB and ANGPTL3 is associated with the risk of early-stage endometriosis. The development of lipid-lowering drugs to treat endometriosis is of potential clinical interest.

The impact of surgical treatment for deep endometriosis: metabolic profile, quality of life and psychological aspects

Objective

To evaluate the effects of surgical treatment of deep endometriosis on the metabolic profile, quality of life and psychological aspects.

Methods

Prospective observational study, carried out with women of reproductive age diagnosed with deep endometriosis, treated in a specialized outpatient clinic, from October/2020 to September/2022, at a University Hospital in Fortaleza - Brazil. Standardized questionnaires were applied to collect data on quality of life and mental health, in addition to laboratory tests to evaluate dyslipidemia and dysglycemia, at two moments, preoperatively and six months after surgery. The results were presented using tables, averages and percentages.

Results

Thirty women with an average age of 38.5 years were evaluated. Seven quality of life domains showed improved scores: pain, control and impotence, well-being, social support, self-image, work life and sexual relations after surgery (ES ≥ 0.80). There was an improvement in mental health status with a significant reduction in anxiety and depression postoperatively. With the metabolic profile, all average levels were lower after surgery: total cholesterol 8.2% lower, LDL 12.8% lower, triglycerides 10.9% lower, and fasting blood glucose 7.3% lower (p < 0.001).

Conclusion

Surgical treatment of deep endometriosis improved the quality of life and psychological aspects of patients. The lipid profile of patients after laparoscopy was favorable when compared to the preoperative lipid profile.

Evaluation of atherosclerosis-related biomarkers during perimenopause: A prospective cohort study in women with endometriosis

AIM

Endometriosis is linked to asymptomatic atherosclerosis and increases the risk of cardiovascular disease (CVD). Vascular function tests are used to assess atherosclerosis, an important indicator of CVD development. In this study, we aimed to evaluate atherosclerosis-related biomarkers, such as vascular function tests and laboratory data, in perimenopausal women with endometriosis.

METHODS

This prospective cohort study enrolled 207 women (≥40 years old) with endometriosis. Laboratory data, ankle brachial index (ABI), and cardio-ankle vascular index (CAVI) were evaluated.

RESULTS

The mean age, CAVI, and ABI of the participants at the initial examination were 45.02 years, 6.9 ± 0.6, and 1.07 ± 0.06, respectively. In multiple regression analysis, no factor was associated with CAVI, but ABI was significantly correlated with elevated total cholesterol (TC), low-density lipoprotein cholesterol, and estradiol (partial regression coefficient [β] = -0.00074, p = 0.017; β = -0.00075, p = 0.033; and β = -0.00022, p = 0.015, respectively). The annual rate of change in CAVI showed a positive correlation with TC and pentosidine and a negative correlation with history of hormone therapy. Neither correlation was strong. In a comparison of three groups classified by the annual rate of change in CAVI, the group with the severe change had a higher level of pentosidine. In adjusted multinomial logistic regression analysis, high pentosidine levels were a risk factor for increased rate of change in CAVI.

CONCLUSIONS

The association between CAVI and serum markers related to lipid metabolism and ovarian function was mild. Longitudinal analysis of CAVI showed an association with pentosidine, which may be helpful in assessing atherosclerosis risk in women with endometriosis during perimenopause.

Endometriosis promotes atherosclerosis in a murine model

BACKGROUND

Epidemiologic studies have demonstrated an association between endometriosis and the subsequent development of cardiovascular disease. The direct effect of endometriosis on the progression of atherosclerotic, if any, has not been previously characterized. Endometriosis leads to systemic inflammation that could have consequences for cardiovascular health. Here, we reported the effects of endometriosis on the development of atherosclerosis in a murine model.

OBJECTIVE

This study aimed to determine the contribution of endometriosis in promoting cardiovascular disease in a murine model of endometriosis.

STUDY DESIGN

Endometriosis was induced in 18 apolipoprotein E-null mice, the standard murine model used to study atherosclerosis. Mice of the same strain were used as controls (n=18) and underwent sham surgery without inducing endometriosis. The formation of endometriotic lesions was confirmed after 25 weeks of induction. Atherosclerotic lesions were subjected to hematoxylin and eosin staining followed by measurement of the aortic root luminal area and wall thickness. The whole aorta was isolated, and Oil Red O staining was performed to quantify the lipid deposits or plaque formation; moreover, biochemical assays were carried out in serum to determine the levels of lipids and inflammatory-related cytokines.

RESULTS

Apolipoprotein E mice with endometriosis exhibited increased aortic atherosclerosis compared with controls as measured using Oil Red O staining (7.9% vs 3.1%, respectively; P=.0004). Mice with endometriosis showed a significant 50% decrease in the aortic luminal area compared with sham mice (0.85 mm2 vs 1.46 mm2; P=.03) and a significant increase in aortic root wall thickness (0.22 mm vs 0.15 mm; P=.04). There was no difference in the lipoprotein profile (P<.05) between mice with endometriosis and sham mice. The serum levels of inflammatory cytokines interleukin 1 alpha, interleukin 6, interferon gamma, and vascular endothelial growth factor were significantly (P<.05)increased in the endometriosis mice.

CONCLUSION

Our study used a murine model to determine the effect of endometriosis on atherosclerosis. Inflammation-related cytokines interleukin 1 alpha, interleukin 6, interferon gamma, and vascular endothelial growth factor (angiogenic factor) released by endometriotic lesions may contribute to the increased cardiovascular risks in women with endometriosis. To reduce the risk of cardiovascular disease, early identification and treatment of endometriosis are essential. Future treatments targeting inflammatory cytokines may help reduce the long-term risk of cardiovascular disease in women with endometriosis.

Reduced cardiovascular risks in women with endometriosis or polycystic ovary syndrome carrying a common functional IGF1R variant

STUDY QUESTION

Is the increased future cardiovascular risk seen in women with endometriosis or polycystic ovary syndrome (PCOS) mitigated by functional insulin-like growth factor-1 receptor (IGF1R) single-nucleotide polymorphism (SNP) rs2016347 as previously shown in women with hypertensive disorders of pregnancy?

SUMMARY ANSWER

This cohort study found that women with endometriosis or PCOS who carry a T allele of IGF1R SNP rs2016347 had a reduced future risk of developing cardiovascular disease (CVD) and associated risk factors, with risk reduction dependent on cohort era.

WHAT IS KNOWN ALREADY

Women with endometriosis or PCOS have been shown to have an increased future risk of CVD and associated risk factors with limited predictive ability.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study took place in the Nurses' Health Study 2 (NHS2), which enrolled 116 430 participants in 1989 who were followed through 2015. The study population was analyzed in its entirety, and subdivided into entry (pre-1989) and after entry (post-1989) exposure cohorts. All NHS2 participants were eligible for inclusion in the study, 9599 (8.2%) were excluded for missing covariates.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The NHS2 enrolled female registered nurses from 14 different states who ranged in age from 25 to 42 years at study entry. Data were collected from entry and biennial questionnaires, and analysis conducted from November 2020 to June 2021. Cox proportional hazard models were used to assess risk of CVD, hypertension (HTN), hypercholesterolemia (HC) and type 2 diabetes, both with and without genotyping for rs2016347.

MAIN RESULTS AND THE ROLE OF CHANCE

While women without endometriosis or PCOS, as a whole, demonstrated no impact of genotype on risk in either cohort, women with endometriosis carrying a T allele had a lower risk of CVD (hazard ratio (HR), 0.48; 95% CI, 0.27-0.86, P = 0.02) and HTN (HR, 0.80; 95% CI, 0.66-0.97, P = 0.03) in the pre-1989 cohort, while those in the post-1989 cohort had a decrease in risk for HC (HR, 0.76; 95% CI, 0.62-0.94, P = 0.01). Women with PCOS in the post-1989 cohort showed a significant protective impact of the T allele on HTN (HR, 0.44; 95% CI, 0.27-0.73, P = 0.002) and HC (HR, 0.62; 95% CI, 0.40-0.95, P = 0.03).

LIMITATIONS, REASONS FOR CAUTION

Data on specific endometriosis lesion locations or disease stage, as well as on PCOS phenotypes were lacking. In addition, data on systemic medical treatments beyond the use of oral contraceptives were missing, and these treatments may have confounded the results.

WIDER IMPLICATIONS OF THE FINDINGS

These findings implicate systemic dysregulation of the insulin-like growth factor-1 axis in the development of HTN, HC and clinical CVD in endometriosis and PCOS, suggesting a common underlying pathogenetic mechanism.

STUDY FUNDING/COMPETING INTEREST(S)

The NHS2 infrastructure for questionnaire data collection was supported by National Institute of Health (NIH) grant U01CA176726. This work was also supported in part by NIH and National Cancer Institute grant U24CA210990; as well, research effort and publication costs were supported by the Elizabeth MA Stevens donor funds provided to the Buck Institute for Research on Aging. The authors declare they have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Inflammatory MicroRNAs and the Pathophysiology of Endometriosis and Atherosclerosis: Common Pathways and Future Directions Towards Elucidating the Relationship

Emerging data indicates an association between endometriosis and subclinical atherosclerosis, with women with endometriosis at a higher risk for cardiovascular disease later in life. Inflammation is proposed to play a central role in the pathophysiology of both diseases and elevated levels of systemic pro-inflammatory cytokines including macrophage migration inhibitory factor (MIF), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) are well documented. However, a thorough understanding on the mediators and mechanisms which contribute to altered cytokine expression in both diseases remain poorly understood. MicroRNAs (miRNAs) are important post-transcriptional regulators of inflammatory pathways and numerous studies have reported altered circulating levels of miRNAs in both endometriosis and atherosclerosis. Potential contribution of miRNA-mediated inflammatory cascades common to the pathophysiology of both diseases has not been evaluated but could offer insight into common pathways and early manifestation relevant to both diseases which may help understand cause and effect. In this review, we discuss and summarize differentially expressed inflammatory circulating miRNAs in endometriosis subjects, compare this profile to that of circulating levels associated with atherosclerosis when possible, and then discuss mechanistic studies focusing on these miRNAs in relevant cell, tissue, and animal models. We conclude by discussing the potential utility of targeting the relevant miRNAs in the MIF-IL-6-TNF-α pathway as therapeutic options and offer insight into future studies which will help us better understand not only the role of these miRNAs in the pathophysiology of both endometriosis and atherosclerosis but also commonality between both diseases.

Endometriosis and cardiovascular disease

Endometriosis is a chronic gynaecological disease affecting 1 in 10 reproductive-age women. It is defined as the presence of endometrium-like tissue outside the uterus. Beyond this placid anatomical definition, endometriosis is a complex, hormonal, inflammatory, and systemic condition that poses significant familial, psychological, and economic burden. The interaction between the cardiovascular system and endometriosis has become a field of interest as the underlying mutual mechanisms become better understood. On the basis of accumulating fundamental and clinical evidence, it is likely that there exists a close relationship between endometriosis and the cardiovascular system. Therefore, investigating the endometriosis-cardiovascular interaction is highly clinically significant. In this review, we highlight our current understanding of the pathophysiology of endometriosis with systemic hormonal, pro-inflammatory, pro-angiogenic, immunologic, and genetic processes beyond the peritoneal microenvironment. Additionally, we provide current clinical evidence about how endometriosis interacts with cardiovascular risk factors and cardiovascular disease (CVD). To date, only small associations between endometriosis and CVD have been reported in observational studies, inherently limited by the potential influence of unmeasured confounding. Cardiovascular disease in women with endometriosis remains understudied, under-recognized, and underdiagnosed. More detailed study of the cardiovascular-endometriosis interaction is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention.

Nonhormonal therapy for endometriosis: a randomized, placebo-controlled, pilot study of cabergoline versus norethindrone acetate

Objective

To estimate the efficacy and safety of a novel nonhormonal therapeutic agent, cabergoline, compared with that of the standard clinical therapy, norethindrone acetate (NETA), for the treatment of endometriosis-associated pain in young women with endometriosis.

Design

Randomized, double-blind, placebo-controlled pilot study.

Setting

Tertiary care center.

Patient(s)

Women (n = 9) with surgically confirmed endometriosis.

Intervention(s)

A random, double-blind assignment to either NETA (5 mg/day) + placebo twice weekly or cabergoline (0.5 mg) twice weekly + placebo daily for 6 months.

Main Outcome Measure(s)

We collected the measures of pelvic pain and laboratory parameters every 3 months.

Result(s)

We observed a decrease in pain scores and increase in pain relief in women randomized to receive cabergoline, who appeared to show similar or more improvements than women treated with NETA. The serum measures of vascular endothelial growth factor receptor 1 declined over 6 months in those who received cabergoline. Cabergoline was well tolerated, and no serious adverse events occurred.

Conclusion(s)

Safe, effective adjunct treatments are lacking for patients with endometriosis who do not respond to standard care. Because the growth of endometriosis requires angiogenesis, blood vessel growth is an attractive therapeutic target. This pilot study suggests that cabergoline, a vascular endothelial growth factor pathway inhibitor, is an effective therapeutic option for women with chronic pain due to endometriosis. Building upon this investigation, we will conduct larger, randomized trials of cabergoline, advancing research on the best treatments for endometriosis—particularly disease resistant to hormonal therapies.

Clinical Trial Registration Number

clinicaltrials.gov; registration number NCT02542410.

Endometriosis Is Associated with an Increased Risk of Coronary Artery Disease in Asian Women

Endometriosis is a common systemic chronic inflammatory disease. Inflammation is the key mechanism responsible for the development of endothelial dysfunction and atherosclerosis. We aimed to investigate the risk of coronary artery disease (CAD) among Asian women with endometriosis. This retrospective population-based cohort study included patients with endometriosis diagnosed from 2000 to 2012 and registered in the Longitudinal Health Insurance Database, Taiwan. The comparison cohort (those without endometriosis) were selected (1:4) by matching the age frequency and the index year. We followed up the patients until the diagnosis of CAD (ICD-9-CM codes: 410-414, A270, and A279), withdrawal from the National Health Insurance system, death, or the end of the study. We used a multivariable-adjusted Cox proportional hazard model for evaluating the risk of CAD. We included 19,454 patients with endometriosis and 77,816 women as a comparison group. The mean age of the women at the diagnosis of endometriosis was 37.4 years. A total of 3245 women developed CAD in both groups during a median follow-up of 7 years. The incidence of CAD was higher in women with endometriosis than in those without (5.96 vs. 4.38 per 10,000 person-years; adjusted hazard ratio [95% confidence interval], 1.34 [1.22-1.47]). In conclusion, Asian women with endometriosis had a significantly higher risk of CAD. Further large-scale studies are needed to elucidate the cause-effect relationship between endometriosis and CAD.

Role of endometriosis in defining cardiovascular risk: a gender medicine approach for women's health

The relationship between endometriosis and subclinical atherosclerosis represents an emerging topic in women's health, as women with endometriosis are at higher risk of cardiovascular disease later in life. We investigated metabolic parameters and indirect endothelial markers related to atherosclerosis, in women suffering from stage III/IV of endometriosis compared with women without endometriosis. The study population comprised 643 women: 92 women (14.3%) with stage III/IV of endometriosis and 551 (85.7%) without endometriosis. By analyzing biohumoral parameters we observed a significant increased total cholesterol (p = 0.01), LDL-C (p = 0.01), triglycerides (p = 0.05) and homocysteinaemia (p = 0.04), lower vitamin B6 and folate (p = 0.07 and p = 0.03, respectively) values, and higher high-sensitive C reactive protein (p = 0.05) concentrations in stage III/IV in comparison to those observed in women without endometriosis. After adjustment for traditional cardiovascular risk factors, the poorer lipid profile (total cholesterol, LDL-C), as well as Lipoprotein (a), remained significantly associated with severity of endometriosis (p = 0.01 and p = 0.03, respectively). Our findings highlight the role of endometriosis as a gender-specific cardiovascular risk factor. The clinical relevance of our study lies in identifying women with stage III/IV of endometriosis at higher risk of atherosclerotic disease, who could benefit from an early cardiovascular screening to control future cardiovascular risk.

The "Hitchhiker's Guide to the Galaxy" of Endothelial Dysfunction Markers in Human Fertility

Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and represents the first step in the pathogenesis of cardiovascular diseases. The evaluation of endothelial health is fundamental in clinical practice and several direct and indirect markers have been suggested so far to identify any alterations in endothelial homeostasis. Alongside the known endothelial role on vascular health, several pieces of evidence have demonstrated that proper endothelial functioning plays a key role in human fertility and reproduction. Therefore, this state-of-the-art review updates the endothelial health markers discriminating between those available for clinical practice or for research purposes and their application in human fertility. Moreover, new molecules potentially helpful to clarify the link between endothelial and reproductive health are evaluated herein.

Associations of Endometriosis and Hormone Therapy With Risk of Hyperlipidemia

Using claims data from the universal health insurance program of Taiwan, we conducted a retrospective cohort study to investigate whether endometriosis and hormone therapy are associated with the risk of developing hyperlipidemia. We selected 9,155 women aged 20-55 years with endometriosis diagnosed during the period 2000-2013 and 212,641 women without endometriosis with a median follow-up time of 7 years. Among patients with endometriosis, 86% of cases were identified on the basis of diagnosis codes with an ultrasound claim, and 14% were defined by diagnostic laparoscopy or surgical treatments. In a Cox proportional hazards model, the adjusted hazard ratio was 1.30 (95% confidence interval (CI): 1.19, 1.41) for all women, 1.04 (95% CI: 0.81, 1.32) for women under 35 years of age, 1.17 (95% CI: 1.03, 1.32) for women aged 35-44 years, and 1.34 (95% CI: 1.18, 1.52) for women aged 45-54 years. Hysterectomy and/or bilateral oophorectomy accounted for 46.9% of the association between endometriosis and hyperlipidemia, and hormone therapy accounted for 21.6%. Among women with endometriosis, the marginal structural model approach adjusting for time-varying hysterectomy/bilateral oophorectomy showed no association between use of hormone medications and risk of hyperlipidemia. We concluded that women with endometriosis are at increased risk of hyperlipidemia; use of hormone therapy by these women was not independently associated with the development of hyperlipidemia.

Atherosclerotic cardiovascular disease in women with endometriosis: a systematic review of risk factors and prospects for early surveillance

Endometriosis and atherosclerotic cardiovascular disease (ASCVD) share similar pathogenic mechanisms. Hence, this systematic review evaluates the association between endometriosis and lifetime ASCVD risk including co-prevalence with dyslipidaemia, atherosclerosis and non-invasive markers of endothelial dysfunction. The electronic databases Embase, PubMed, MEDLINE, Cochrane Register of Trials and ClinicalTrials.gov were systematically searched for relevant articles. Two prospective cohort studies demonstrated an increased lifetime ASCVD risk after controlling for demographic and lifestyle confounders in women with endometriosis, as measured by higher incidence of myocardial infarction (relative risk [RR] 1.52), angiography-confirmed angina (RR 1.91), or requiring coronary artery bypass graft surgery (RR 1.35). Among 10 studies that included 407 patients with surgically proven endometriosis and 557 controls, RR of developing hypercholesterolemia and hypertension were 1.25 and 1.14, respectively, while higher serum lipoprotein a and lower paraoxonase 1 levels were found in women with endometriosis that was negatively correlated with stage of disease (r = -0.74, P < 0.0001). Hence, currently available evidence suggests that women with endometriosis are at higher lifetime risk of developing ASCVD than women without endometriosis. However, robust causal evidence is still lacking and future studies are needed to determine whether women with endometriosis represent a high-risk population for lifelong ASCVD risk.

Infertility: a marker of future health risk in women?

Infertility, may be a harbinger for future health risk in women, including early mortality. Fertility status itself could serve as an early biomarker, (present in a woman's reproductive years) for risk stratification later in life. The relationship between infertility and early mortality involves the impact of nulliparity on future adverse health events, potential sequelae from the underlying cause(s) of infertility, the risks of fertility treatments, as well as the potential for risk reduction from a healthy pregnancy. This complex interplay coupled with difficulties ascertaining infertility on a population level has presented unique challenges to assessing infertility and early mortality risk. With further study, a better understanding the role of fertility status in health at various stages of life may provide unique opportunities for surveillance and risk reduction.

Clinicopathologic characteristics of ovarian clear cell carcinoma in the background of endometrioma: a surveillance strategy for an early detection of malignant transformation in patients with asymptomatic endometrioma

Objective

This study aimed to analyze the clinical features of clear cell carcinoma in relation to endometriosis and to determine an appropriate surveillance strategy for the early detection of malignant transformation of endometrioma in asymptomatic patients.

Methods

We retrospectively reviewed the clinicopathologic data of 50 patients with ovarian clear cell carcinoma. Clinicopathologic characteristics, treatment outcomes, and the association between endometriosis and the risk of malignant transformation were analyzed.

Results

Ten (20%) patients had been diagnosed with endometrioma before the diagnosis of clear cell carcinoma. The median period from the diagnosis of endometrioma to clear cell carcinoma diagnosis was 50 months (range, 12–213 months). After complete staging surgery, histological confirmation of endometriosis was possible in 35 (70%) patients. Of the 50 patients, 39 (78%) had not undergone any gynecologic surveillance until the onset of symptoms, at which time many of them presented with a rapidly growing pelvic mass (median 10 cm, range 4.6–25 cm). With the exception of 2 patients, all cancer diagnoses were made when the patients were in their late thirties, and median tumor size was found to increase along with age. Asymptomatic patients (n=11) who had regular gynecologic examinations were found to have a relatively smaller tumor size, lesser extent of tumor spread, and lower recurrence rate (P=0.011, 0.283, and 0.064, respectively). The presence of endometriosis was not related to the prognosis.

Conclusion

Considering the duration of malignant transformation and the timing of cancer diagnosis, active surveillance might be considered from the age of the mid-thirties, with at least a 1-year interval, in patients with asymptomatic endometrioma.