Relationship between the severity of endometriosis symptoms (dyspareunia, dysmenorrhea and chronic pelvic pain) and the spread of the disease on ultrasound

Menstrual Blood Donation for Endometriosis Research: A Cross-Sectional Survey on Women's Willingness and Potential Barriers

An anonymous online survey in French was used to assess if endometriosis patients would be as ready as unaffected women to donate their menstrual blood for biological research on endometriosis and evaluate potential barriers to such donation. It was distributed in September 2022 by social media and two mailing lists, including a French patient organization. The questionnaire assessed participant age and brief medical history (hormonal contraception, endometriosis diagnosis, type of endometriosis), menstrual experience (menstrual blood abundance, dysmenorrhea), and whether participants would donate menstrual blood. Women who self-declared with an established endometriosis diagnosis versus no endometriosis were compared. Seven hundred seventy-eight women answered the survey. Among women with menstruation (n = 568), 78% are willing to donate menstrual blood for research. Importantly, this proportion was higher in women who declared having an established endometriosis diagnosis (83%, n = 299) compared to self-declared unaffected women (68%, n = 134, p < 0.001). The previous use of a menstrual cup and dysmenorrhea were significantly associated with the willingness to donate menstrual blood, while the use of hormonal contraception was significantly associated with an unwillingness to donate. Only the previous use of the menstrual cup had a predictive value for menstrual blood donation. No significant relationship was observed between menstrual blood donation and age, heavy menstrual bleeding and in endometriosis patients, endometriosis subtypes. In conclusion, women affected or not by endometriosis are largely willing to donate their menstrual blood for research on endometriosis, dysmenorrhea is not a barrier for donation, and women who use a menstrual cup are the more likely to donate.

Reproducibility of #Enzian classification by transvaginal ultrasound and its correlation with symptoms

Background

The #Enzian classification represents a system to describe endometriotic lesions during surgery. Its use is well established in correlating ultrasound and surgical findings.

Objectives

To describe interobserver reproducibility of ultrasound use and symptom correlation with compartments involved using #Enzian classification.

Materials and Methods

Two experienced operators performed transvaginal sonography (TVS) in 52 patients affected by pelvic endometriosis. A rate agreement was determined. A further 200 women with endometriotic TVS signs, with no previous surgery and not taking any hormonal therapy, were staged by one of three different operators according to the #Enzian (compartments A, B, C, O, T, FA, FB, FI, FU, FO). Statistical analysis compared all the compartments, as single or associated, with single or combined symptoms (dysmenorrhea, dyspareunia, heavy menstrual bleeding - HMB, bowel symptoms).

Main outcome measures

Evaluation of the reproducibility of #Enzian classification in assessing pelvic endometriosis among different operators using TVS, and of possible associations between symptoms and specific #Enzian compartments.

Results

Excellent agreement between the two operators in evaluating almost all the compartments (k >0.8) was observed. Dysmenorrhea did not correlate with any specific compartment. We observed a significant association between dyspareunia and B compartment (p=0.02). HMB is associated with FA (p=0.02). Bowel symptoms were associated with B (p=0.02). Combining more symptoms, we observed more significant associations with different compartments.

Conclusions

#ENZIAN classification is reproducible in the evaluation of pelvic endometriosis. Some symptoms are correlated to specific ultrasound signs of the disease.

What is new?

An accurate evaluation of symptoms could guide TVS examination to detect specific endometriotic lesions and establish the best management for the patients.

The effect of antioxidant supplementation on dysmenorrhea and endometriosis-associated painful symptoms: a systematic review and meta-analysis of randomized clinical trials

This study aimed to review randomized controlled trials (RCTs) investigating the effects of dietary antioxidant supplements on the severity of endometriosis-related pain symptoms. The PubMed/Medline, Scopus, and Web of Science databases were searched until April 2022. Additionally, we manually searched the reference lists. Endpoints were summarized as standardized mean difference (SMD) with 95% confidence intervals (CIs) in a random-effects model. The I2 statistic was used to assess heterogeneity. Ten RCTs were included in this meta-analysis. Overall, 10 studies were related to dysmenorrhea, four to dyspareunia, and four to pelvic pain. Antioxidants significantly reduced dysmenorrhea (SMD, -0.48; 95% CI, -0.82 to -0.13; I2=75.14%). In a subgroup analysis, a significant reduction of dysmenorrhea was observed only in a subset of trials that administered vitamin D (SMD, -0.59; 95% CI, -1.13 to -0.06; I2=69.59%) and melatonin (SMD, -1.40; 95% CI, -2.47 to -0.32; I2=79.15%). Meta-analysis results also suggested that antioxidant supplementation significantly improved pelvic pain (SMD, -1.51; 95% CI, -2.74 to -0.29; I2=93.96%), although they seem not to have a significant beneficial impact on the severity of dyspareunia. Dietary antioxidant supplementation seems to beneficially impact the severity of endometriosis-related dysmenorrhea (with an emphasis on vitamin D and melatonin) and pelvic pain. However, due to the relatively small sample size and high heterogeneity, the findings should be interpreted cautiously, and the importance of further well-designed clinical studies cannot be overstated.

An artificial intelligence approach for investigating multifactorial pain-related features of endometriosis

Endometriosis is a debilitating, chronic disease that is estimated to affect 11% of reproductive-age women. Diagnosis of endometriosis is difficult with diagnostic delays of up to 12 years reported. These delays can negatively impact health and quality of life. Vague, nonspecific symptoms, like pain, with multiple differential diagnoses contribute to the difficulty of diagnosis. By investigating previously imprecise symptoms of pain, we sought to clarify distinct pain symptoms indicative of endometriosis, using an artificial intelligence-based approach. We used data from 473 women undergoing laparoscopy or laparotomy for a variety of surgical indications. Multiple anatomical pain locations were clustered based on the associations across samples to increase the power in the probability calculations. A Bayesian network was developed using pain-related features, subfertility, and diagnoses. Univariable and multivariable analyses were performed by querying the network for the relative risk of a postoperative diagnosis, given the presence of different symptoms. Performance and sensitivity analyses demonstrated the advantages of Bayesian network analysis over traditional statistical techniques. Clustering grouped the 155 anatomical sites of pain into 15 pain locations. After pruning, the final Bayesian network included 18 nodes. The presence of any pain-related feature increased the relative risk of endometriosis (p-value < 0.001). The constellation of chronic pelvic pain, subfertility, and dyspareunia resulted in the greatest increase in the relative risk of endometriosis. The performance and sensitivity analyses demonstrated that the Bayesian network could identify and analyze more significant associations with endometriosis than traditional statistical techniques. Pelvic pain, frequently associated with endometriosis, is a common and vague symptom. Our Bayesian network for the study of pain-related features of endometriosis revealed specific pain locations and pain types that potentially forecast the diagnosis of endometriosis.

Relaxed fibronectin: a potential novel target for imaging endometriotic lesions

BACKGROUND

Endometriosis is characterized by the ectopic occurrence of endometrial tissue. Though considered benign, endometriotic lesions possess tumor-like properties such as tissue invasion and remodeling of the extracellular matrix. One major clinical hurdle concerning endometriosis is its diagnosis. The diagnostic modalities ultrasound and MRI are often unable to detect all lesions, and a clear correlation between imaging and clinical symptoms is still controversial. Therefore, it was our aim to identify a potential target to image active endometriotic lesions.

RESULTS

For our studies, we employed the preclinical radiotracer [111In]In-FnBPA5, which specifically binds to relaxed fibronectin-an extracellular matrix protein with key functions in homeostasis that has been implicated in the pathogenesis of diseases such as cancer and fibrosis. We employed this tracer in biodistribution as well as SPECT/CT studies in mice and conducted immunohistochemical stainings on mouse uterine tissue as well as on patient-derived endometriosis tissue. In biodistribution and SPECT/CT studies using the radiotracer [111In]In-FnBPA5, we found that radiotracer uptake in the myometrium varies with the estrous cycle of the mouse, leading to higher uptake of [111In]In-FnBPA5 during estrogen-dependent phases, which indicates an increased abundance of relaxed fibronectin when estrogen levels are high. Finally, immunohistochemical analysis of patient samples demonstrated that there is preferential relaxation of fibronectin in the proximity of the endometriotic stroma.

CONCLUSION

Estrous cycle stages characterized by high estrogen levels result in a higher abundance of relaxed fibronectin in the murine myometrium. This finding together with a first proof-of-concept study employing human endometriosis tissues suggests that relaxed fibronectin could be a potential target for the development of a diagnostic radiotracer targeting endometriotic lesions. With [111In]In-FnBPA5, the matching targeting molecule is in preclinical development.

A preoperative predictive model for stage IV endometriosis

This was a retrospective study that evaluated a total of 280 patients who underwent surgery for complete removal of endometriosis to develop and validate the predictive model for stage IV endometriosis. The differences between stage I-III and stage IV endometriosis were performed by logistic regression. A model for the prediction of stage IV endometriosis was constructed, which was subsequently validated. The independent variables were visual analogue scale (VAS)≥4 [3.855, 95% confidence interval (CI): 1.675-8.871, p = 0.002], painful nodularity on uterosacral ligaments (13.954, 95% CI: 1.658-117.423, p = 0.015), and bilateral endometriosis (5.933, 95% CI: 1.931-18.225, p = 0.002). The AUC of the model was 0.777, with a sensitivity of 71.9% and specificity of 76.3% for stage IV endometriosis. Therefore, a complete collection of patient information prior to surgery, asking about pain and VAS scores, careful completion of pelvic examinations, and application of imaging techniques are conducive to better diagnosis and prediction of advanced endometriosis.IMPACT STATEMENTWhat is already known on this subject? Endometriosis, a chronic disease causing pain and infertility, is characterised by endometrial-like tissue outside the uterine cavity, which is often treated via surgery at present. Considering the risks of surgery, it is necessary to identify patients with stage IV endometriosis through non-invasive predictive models for adequate preparation for surgery. However, there is no reliable non-invasive predictive model now, despite utilisation of patient medical history, symptoms especially pain-related ones, pelvic examinations, laboratory examinations, and images in the preoperative diagnosis of endometriosis in the clinic.What do the results of this study add? A model developed based on three simple, accessible and non-invasive indicators displays good performance in predicting stage IV endometriosis.What are the implications of these findings for clinical practice and/or further research? It is conducive to diagnosing and predicting advanced endometriosis before surgery, so as to reduce the difficulty and improve the safety of surgery.

Diet associations in endometriosis: a critical narrative assessment with special reference to gluten

Endometriosis is characterized by the presence of endometrium-like tissue outside the uterus. The etiology remains largely unknown. Despite adequate treatment, patients can still experience symptoms or side effects resulting in therapy incompliance and in self-management strategies such as dietary measures is increasing. A gluten free diet is thought to be contributory in reducing endometriosis-related pain, thereby optimizing quality of life. However, data is conflicting and currently provides no evidence for causality. This narrative review aims to put the effect of dietary self-management strategies on endometriosis in a balanced perspective, especially the effect of gluten and a gluten free diet. Several studies have found a strong overlap in symptoms, metabolic and immune responses associated with endometriosis and those associated with celiac disease, ulcerative colitis, Crohn's disease, irritable bowel syndrome and non-celiac wheat sensitivity. However, it remains unclear whether these diseases and/or disorders are causal to an increased risk of endometriosis. Some studies have found a positive effect on the risk of endometriosis, endometriosis-related symptoms and quality of life (QoL) when women either avoided certain nutrients or foods, or applied a specific nutrient supplementation. This includes the avoidance of red meat and omega-3, an increasing intake of foods rich in anti-oxidants, micronutrients and dietary fibers (e.g., fruit, vegetables) and the appliance of a gluten free diet. However, data from the available studies were generally graded of low quality and it was noted that placebo and/or nocebo effects influenced the reported positive effects. In addition, such effects were no longer seen when adjusting for confounders such as overweight, when a translation was made from in vitro to in vivo, or when the nutrients were not supplemented as isolated sources but as part of a mixed daily diet. Finally, some studies showed that long-term adherence to a gluten free diet is often associated with an impaired diet quality and nutrient intake, leading to negative health outcomes and reduced QoL. Concluding, scientific evidence on the efficacy of dietary interventions on well-defined clinical endpoints of endometriosis is lacking and recommending a gluten free diet to women solely diagnosed with endometriosis should therefore not be advised.

Risk factors for recurrent endometriosis after conservative surgery in a quaternary care center in southern Thailand

OBJECTIVES

To determine the 2-year recurrence rate of endometriosis after conservative surgery and the risk factors for recurrence.

METHODS

This study retrospectively analyzed women with endometriosis who underwent conservative surgery and had at least a 2-year follow-up at a quaternary care hospital in southern Thailand from January 2000 to December 2019. Recurrent endometriosis was defined as either presence of endometrioma with a diameter ≥ 2 cm for more than three consecutive menstrual cycles or relapse of pelvic pain with the same or higher visual analog scale (VAS) score as before surgery. Multivariate logistic regression analysis was used to identify the risk factors for recurrence.

RESULTS

The median (interquartile range [IQR]) age was 34 (29, 38) years in 362 cases and nearly three-quarters (74.2%) were nulliparous. Cyclic pain was the most common clinical presentation (48.9%) and the median (IQR) VAS score of pelvic pain was 6 (5, 9). Ovarian cystectomy was the most common procedure (68.1%). The 2-year recurrent endometriosis rate after conservative surgery was 23.2%, and the overall recurrence rate was 56.4%. The risk factors of recurrence were preoperative moderate to severe pelvic pain (adjusted odds ratio [aOR] 1.93; 95% confidence interval [CI], 1.12-3.34; p = 0.017), adhesiolysis/ablation/ovarian cystectomy without unilateral oophorectomy (aOR 2.71; 95% CI, 1.40-5.23; p = 0.002), and duration of postoperative hormonal treatment < 24 months (aOR 10.58; 95% CI, 5.47-20.47; p < 0.001).

CONCLUSION

The 2-year recurrence rate after conservative surgery for endometriosis was 23.2%. Preoperative moderate to severe pelvic pain, procedures except unilateral oophorectomy, and postoperative hormonal treatment < 24 months were risk factors for recurrence.

A better quality of life could be achieved by applying the endometriosis diet: a cross-sectional study in Dutch endometriosis patients

RESEARCH QUESTION

Does the endometriosis diet positively affect quality of life (QoL) in women diagnosed with endometriosis?

DESIGN

A cross-sectional study was performed, recruiting women using the website and online peer platforms from the Dutch Endometriosis Society. In total, 211 women with a self-reported diagnosis of endometriosis were included in the study. They completed a questionnaire on the six QoL domains based on the conversation tool 'My Positive Health'. Women who adhered to the endometriosis diet were compared with women who did not. A distinction was made between strict (score ≥8 on a scale of 0-10) and less strict adherence to the diet.

RESULTS

A significantly higher score was seen in all six QoL domains in women who adhered to the endometriosis diet (n = 90) compared with women who did not (n = 121) (range P < 0.001 to P = 0.043). Furthermore, women with strict adherence (n = 48) compared to less strict adherence (n = 42) reported significantly higher scores in all six QoL domains (range P = 0.005 to 0.05). Women diagnosed with endometriosis more than 10 years ago (n = 13) adhered to the endometriosis diet significantly less often than women that were diagnosed more recently (n = 163; range P = 0.005 to 0.046).

CONCLUSION

The endometriosis diet was associated with a better QoL in Dutch women with endometriosis. Strict adherence showed higher QoL scores compared with less strict adherence. Therefore, more research is needed to clarify the mechanism of this beneficial effect and to identify facilitators and barriers to dietary adjustments in patients with endometriosis.

Comparison of high-intensity focused ultrasound for the treatment of internal and external adenomyosis based on magnetic resonance imaging classification

OBJECTIVE

To compare the safety and efficacy of high-intensity focused ultrasound (HIFU) treatment for patients with internal or external adenomyosis based on magnetic resonance imaging (MRI) classification.

MATERIALS AND METHODS

A total of 238 patients with internal adenomyosis and 167 patients with external adenomyosis who received HIFU treatment were enrolled. HIFU treatment results and adverse effects between patients with internal and external adenomyosis were compared.

RESULTS

The treatment time and sonication time for patients with external adenomyosis were significantly longer than that for patients with internal adenomyosis. The total energy used and EEF for patients with external adenomyosis were higher than that for patients with internal adenomyosis (p < 0.05). The pre-HIFU median dysmenorrhea score in patients with internal or external adenomyosis was 5 or 8 points, the median score decreased to 1 or 3 points in these two groups at 18-month post-HIFU (p < 0.05). The relief rate of dysmenorrhea was 79.5% in patients with internal adenomyosis, and it was 80.8% in patients with external adenomyosis. The pre-HIFU median menorrhagia score in patients with internal or external adenomyosis was 4 or 3 points, the median score decreased to 1 point in both groups at 18-month post-HIFU with a relief rate of 86.2% and 77.1%, respectively (p = 0.030). No serious complication occurred in any of these patients.

CONCLUSIONS

HIFU is a safe and effective treatment either for patients with internal adenomyosis or external adenomyosis. It seemed that internal adenomyosis is easier to be treated with HIFU and with a higher relief rate of menorrhagia than external adenomyosis.

Inflammation-mediated macrophage polarization induces TRPV1/TRPA1 heteromers in endometriosis

Chronic pelvic pain (CPP) and infertility are the common characteristics of endometriosis. Macrophages and related inflammation play important roles in endometriosis pain. TRPV1 and TRPA1 form a heteromeric channel which is related to endometriosis pain. In the present study, the inflammation-mediated macrophage polarization along with TRPV1/TRPA1 heteromers in endometriosis was investigated in vivo and in vitro. Macrophage polarization and TRPV1/TRPA1 heteromers in endometriosis tissue of patients were assayed, and was further investigated in endometriosis mice by co-culturing macrophages derived from mice in different groups with human endometrium cells. Our results indicated that macrophage polarization, as CD86 and CD206 positive macrophages, were accompanied by TRPV1/TRPA1 heteromers in endometriosis tissues of patients with pain. Inflammatory factors in peritoneal lavage fluid and serum of mice were correlated with TRPV1/TRPA1 expression in endometriosis tissues of mice as well as macrophage polarization which tended to be consistent with TRPV1/TRPA1 heteromers in endometriosis tissue. Moreover, macrophage polarization in enterocoelia induced ectopic endometrial cells migration with the increase in TRPV1/TRPA1 heteromers. Our results suggest that endometriosis-induced celiac inflammation might mediate macrophage polarization along with the increase of TRPV1/TRPA1 heteromers, which may play a key role in endometriosis pain.

Increased expression of IL-37 correlates with TNF-α levels and disease stage in endometriosis patients

Background

IL-37 is an anti-inflammatory cytokine that increases in several inflammatory diseases with the main inducing signal for its production being pro-inflammatory cytokines like TNF-α. We aimed to assess the correlation between peritoneal fluid levels of IL-37 and TNF-α in endometriosis patients and investigate their association with disease stage. Levels of IL-37 and TNF-α were assessed in peritoneal fluid of 50 patients with endometriosis and 23 endometriosis-free females using enzyme-linked immunosorbent assay. We also assessed serum levels of IL-37 using enzyme-linked immunosorbent assay and expression of IL-37 mRNA in peritoneal fluid cells using polymerase chain reaction.

Results

Peritoneal fluid levels of IL-37 and TNF-α were higher in endometriosis patients than in control females. Also, levels were higher in patients with late endometriosis than patients with early endometriosis. In addition, serum levels of IL-37, as well as IL-37 mRNA expression in peritoneal fluid cells, were higher in patients than controls. In endometriosis patients, peritoneal fluid levels of IL-37 positively correlated with levels of TNF-α.

Conclusion

Collectively, our results show increased levels of the anti-inflammatory cytokine IL-37 in endometriosis patients that correlate with levels of the pro-inflammatory cytokine TNF-α, one of the main signals for IL-37 production.

Evaluation of high intensity focused ultrasound treatment for different types of adenomyosis based on magnetic resonance imaging classification

OBJECTIVE

To evaluate the mid-term symptom improvement of patients with different types of adenomyosis based on magnetic resonance imaging (MRI) classification after ultrasound-guided high intensity focused ultrasound (USgHIFU) treatment.

MATERIALS AND METHODS

A total of 321 patients with adenomyosis who underwent HIFU and completed 18-month follow-up were retrospectively reviewed. Based on the relationship between the adenomyotic lesion and the uterine structural components on T2-weighted imaging (T2WI), adenomyotic lesions were classified as internal, external, full thickness and intramural adenomyosis. Based on the extent of the myometrial involvement, these lesions were further subclassified as asymmetric and symmetric adenomyosis.

RESULTS

All patients completed HIFU ablation in one session. The range of median menstrual pain score in patients with asymmetric internal, symmetric internal, asymmetric external, asymmetric full thickness, symmetric full thickness, and intramural adenomyosis was between 6 and 8 points before HIFU, the median menstrual pain score decreased to 2-4 points 18-month post-HIFU (p < .005). The menstrual pain relief rate was 68.3%, 62.1%, 54.7%, 64.1%, 60%, and 100%, respectively. The median menstrual blood volume score range was between 2 and 4 points in the different groups of patients before HIFU, it decreased to 1-3 points 18-month after HIFU with a relief rate of 68.3%, 51.6%, 51.0%, 55.5%, 57.2%, and 100%, respectively. No serious complication occurred in any of these patients.

CONCLUSIONS

Based on our results, USgHIFU is safe and effective in the treatment of patients with different subtypes of adenomyosis with mid-term sustained improvement in symptoms of menstrual pain and menstrual blood volume.

The Diagnostic Accuracy of Galectin-9 for Diagnosis of Endometriosis in Comparison with Laparoscopy

BACKGROUND

Endometriosis is a common devastating gynecological disease with severe complications. Researches on noninvasive diagnostic tests with acceptable accuracy are still ongoing. The purpose of the present study was to evaluate the diagnostic value of serum Galectin-9 (Gal-9) level in comparison with laparoscopic results in endometriosis patients.

METHODS

Sixty-one patients, referred to Booali, Rasool-e-Akram, and Pars Hospitals affiliated to Islamic Azad University of Medical Sciences, were recruited. Patients laparoscopically diagnosed with endometriosis were assigned to the case (n=32) and who diagnosed with other diseases were assigned to the control group (n=29). In general, 56 patients (30 in case and 26 in control group) completed the study. The serum level of Galectin-9 was measured using ELISA method before laparoscopy and was compared between the groups. Next, categorical variables were compared using Chi square and quantitative variables using independent samples t- test or Mann-Whitney U test. The Gal-9 cut-off was calculated using the Youden's index and ROC curve; then, sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratio of Gal-9 were reported. The p<0.05 were considered statistically significant.

RESULTS

Mean serum level of Galectin-9 was 669.3±416.50 pg/ml in the case group and 265.42±492.30 pg/ml in the control group (p=0.001). Considering a cut-off value of 138 pg/ml, Galectin-9 had a sensitivity of 100% and specificity of 88.46% for diagnosis of endometriosis (p<0.001).

CONCLUSION

Galectin-9 measurement is helpful in diagnosis of endometriosis. Future studies are recommended for investigating the generalizability of these results.

Relationship between magnetic resonance imaging-based classification of adenomyosis and disease severity

AIMS

The purpose of this study is to first investigate the correlation between image features and histological findings and the clinical severity of adenomyosis; second, search for imaging features to assess the type and locoregional extension of the disease; and finally, discuss the notation of image-based classification.

METHODS

This paper combines a review of the literature on adenomyosis with a series of cases who underwent surgery at Nara Medical University Hospital.

RESULTS

Currently, there has been a lack of clear, clinically relevant, and internationally acceptable definition and histological classification due to its diverse phenotype. A number of researchers have attempted to standardize the magnetic resonance imaging (MRI) features of adenomyosis. Some researchers have begun studies that relate the subtype classification using MRI to disease severity. There is evidence suggesting that diffuse adenomyosis and intrinsic adenomyosis are correlated with menstrual bleeding, while extrinsic adenomyosis and coexistence of deep infiltrating endometriosis (DIE) are related to pelvic pain. MRI-based classifications that are simple for use in the clinical setting are beginning to be proposed. However, the reliability and validity of these classifications have not yet been verified. A simplified notation is required to discuss the association between the classification and severity of adenomyosis. We introduce case reports using the notation of four items necessary for classification of adenomyosis.

CONCLUSION

There is an urgent need to determine the definitions of terms used in subtype classification and to create and validate a globally unified notation that can predict the severity of adenomyosis symptoms.

A deep insight into pelvic pain and endometriosis: a review of the literature from pathophysiology to clinical expressions

Endometriosis is a chronic inflammatory disease that affects approximately 10% of women of reproductive age. Its clinical manifestations are highly heterogeneous, but pelvic pain is the most frequent, causing functional disability. Cyclic or acyclic chronic pelvic pain (CPP), dysmenorrhea and dyspareunia are frequent symptoms which often compromise all aspects of the women's quality of life (QoL). The pathophysiology of endometriosis-related pain is extremely complex and not always clear. The aim of this literature review is to focus on recent updates on the clinical presentation, the pathophysiology and the most important mechanisms involved in the pathogenesis of pelvic pain in endometriosis. A literature search in the Cochrane library, PubMed, Scopus and web of Science databases has been performed, identifying articles from January 1995 to November 2020. Several processes seem to be involved in the pathogenesis of pain, but many aspects are still unclear. Scientific evidence has shown that a correlation between pain severity and stage of endometriosis rarely occurs, whereas there is a significant correlation between pain and the presence of deep endometriosis. Onset and intensity of pain may be due to a complex process involving central sensitization and peripheral activation of nociceptive pathways as well as dysfunction of the immune system and of the hypothalamic-pituitary-adrenal (HPA) axis. A deeper understanding of these different pathogenetic mechanisms may improve future treatments in women with painful endometriosis.