Association between dysmenorrhea and chronic pain: a systematic review and meta-analysis of population-based studies

Social Determinants of Health and Dysmenorrhea: A Systematic Review

Social determinants of health play a key role in health disparities. Dysmenorrhea is a highly prevalent and impactful public health problem affecting reproductive-age females. Systematically examining social determinants of health in dysmenorrhea is important for identifying gaps in the literature and informing research, policy, and clinical practice to reduce the public health burden associated with dysmenorrhea. The purpose of this systematic review was to synthesize the literature on social determinants of health and dysmenorrhea. The review protocol was prospectively registered. We searched Medline, EMBASE, CINAHL, PsycINFO, Scopus, and Google Scholar through February 2024 using search strategies informed by the literature. Screening of the articles, data extraction, and risk of bias assessment were conducted independently by at least two reviewers on the Covidence platform. Among 2594 unique records screened, 166 met eligibility criteria and were included for data extraction and risk of bias assessment. Evidence suggests traumatic experiences, toxic environmental exposures, female genital mutilation, job-related stress, lack of menstrual education, and low social support were associated with worse dysmenorrhea outcomes. However, evidence was equivocal regarding relationships between dysmenorrhea outcomes and social determinants of health factors, including socioeconomic status, geographical location, race/ethnicity, employment, and religion. Nearly all articles (99.4%) had a high or very high overall risk of bias. Relationships between social determinants of health and dysmenorrhea outcomes were often inconsistent and complicated by heterogeneous study populations and methodologies. More rigorous research examining social determinants of health in dysmenorrhea is needed to inform policy and clinical practice. PERSPECTIVE: This systematic review synthesizes evidence linking social determinants of health and dysmenorrhea. Relationships between SDoH and dysmenorrhea were often equivocal and complicated by heterogeneous study populations and methodologies. We identify directions for future research and SDoH factors that could be addressed clinically (e.g., trauma, menstrual education, occupational stress).

Pain in the enthesis of levator ani muscle: A novel source of chronic pelvic pain

BACKGROUND

Managing chronic pelvic pain (CPP) remains a challenge due to its diverse range of causes. A newly identified anatomical entity known as the enthesis of the levator ani muscle (LAM) and its associated disorders might play a role. This paper describes a novel insight into CPP's origin, aiming to improve accurate diagnosis and treatment.

METHODS

Data were collected from medical records (paper or electronic) retrospectively. The study included 112 patients meeting the criteria, divided into CPP and non-CPP groups. Clinical symptoms, including location of LAM enthesis, referred pain from pain in LAM enthesis, and related lower urinary tract symptoms (LUTSs) were discussed. To identify differences in symptoms between the groups, a Chi-squared test and descriptive analyses were conducted.

RESULTS

Bimanual examination revealed tender sites in the attachment of the LAM to the pubic bone. LAM enthesis pain presumably caused referred pain in at least 10 areas, primarily in the lower abdominal quadrate (40.2%-47.3%) followed by the inguinal area (8.9%-15.1%). Multiple LUTSs were observed, including urinary frequency (72.3%), urgency (42.9%), nocturia (53.6%), residual urine sensation (64.3%), urinary incontinence (30.3%), painful bladder (34.8%), and weak urine stream (47.9%). Patients in the CPP groups experienced significant residual urine sensation (53.6%) and bearing-down sensation (42%) compared to the non-CPP group.

CONCLUSION

Pain in LAM enthesis is a novel cause of pelvic pain and LUTSs that warrants attention for the evaluation and management of CPP.

A multidimensional appraisal of early menstrual pain experience

BACKGROUND

Symptomatic dysmenorrhea is a global problem, affecting more than 40% of menstruating persons. Cross-sectional studies have implicated psychosocial, biological, and sensory factors in dysmenorrhea but the mechanisms are not fully understood. Only a few prospective longitudinal studies have evaluated such factors in relation to the emergence and course of dysmenorrhea at menarche.

OBJECTIVE

This study aimed to describe the initial menstruation experience and to evaluate the association of premenarchal psychosocial and sensory factors with the intensity of dysmenorrhea during the period in the fourth month.

STUDY DESIGN

This was a prospective cohort study of adolescents who completed premenarchal assessments and postmenarchal daily menstrual diaries for their first (n=149) and fourth month periods (n=114). They were recruited shortly before menarche and completed baseline assessments, including psychosocial questionnaires and experimental pain sensitivity (pressure testing, bladder provocation), and their parents completed related pain questionnaires. The relation between the hypothesized premenarchal factors and month 4 dysmenorrhea intensity was evaluated using Kruskal-Wallis and chi-square tests for low (<3 on a 0-10 scale) vs higher (≥3) menstrual pain groups based on maximal pain ratings recorded in a daily diary.

RESULTS

Low levels of dysmenorrhea characterized the first (median, 1; interquartile range, 0-2) and fourth month periods (1; 0-3). Maximal pain ratings increased from the first to the fourth period (3; 1-5 vs 4; 1-6; P=.007). The distribution of dysmenorrhea was multimodal at month 4 with 31.6% of the participants having low levels of maximal pain (1; 0-1) and 68.4% having higher levels (5; 4-6; Hartigan's dip test P<.001). The baseline demographic, psychosocial, and parental pain characteristics were not associated with the development of worse dysmenorrhea. The baseline experimental pain sensitivity, based on pressure pain thresholds, did not differ between the low (15.7 N; 12.5-22.3) and higher (15.0 N; 10.9-21.4]) level dysmenorrhea groups. Baseline bladder pain at first urge also did not differ (low, 6; 0-20 vs higher, 7; 0-19).

CONCLUSION

By their fourth month period, two-thirds of adolescents fell into the higher group for maximal dysmenorrhea, half reported some related impairments in physical activity, and one-seventh reported some related school absence. Premenarchal factors (experimental pain sensitivity, psychosocial profile, parental pain experience) linked to chronic pain emergence in the adult literature did not predict dysmenorrhea intensity, suggesting the dominant factor at menarche may be peripheral afferent activation. Further research is needed to understand the evolution of psychosocial and sensory mechanisms in the development and course of dysmenorrhea.

Understanding Adolescents' Experiences With Menstrual Pain to Inform the User-Centered Design of a Mindfulness-Based App: Mixed Methods Investigation Study

BACKGROUND

Digital interventions are increasingly popular for the provision of nonpharmacological pain interventions, but few exist for adolescents with menstrual pain. User-centered design involves incorporating users across phases of digital health intervention design, development, and implementation and leads to improved user engagement and outcomes. A needs assessment is the first step of this approach.

OBJECTIVE

The goal of this study was to conduct a needs assessment to understand menstrual pain management needs and preferences and mindfulness experiences, preferences, and knowledge of adolescents with menstrual pain to inform the future development of an app for managing menstrual pain.

METHODS

We used an explanatory sequential mixed method design that included a survey followed by focus groups. Adolescents aged 13-17 years completed a survey (n=111) and participated in focus groups (n=16). Data were analyzed using descriptive statistics and thematic content analysis and synthesized to provide specific recommendations based on adolescent responses.

RESULTS

Adolescents (n=111) who completed the survey reported a moderate understanding of mindfulness and menstrual pain. Over three-quarters (n=87, 78%) of participants practiced some form of mindfulness and 87% (n=97) of survey participants used nonpharmacological pain management strategies. Teens had a moderate perception that mindfulness could help their menstrual pain (mean 4.51/10, SD 2.45, with higher scores suggesting more interest). Themes were generated related to mindfulness experiences, menstrual pain knowledge and experiences, and app functionality. These themes underscored adolescents' need for continued support and flexible access to mindfulness activities; their awareness of multiple influences to pain, with potential for further education in this area; and the need for menstrual pain-specific content, along with content relevant to typical day-to-day experiences of adolescents.

CONCLUSIONS

Adolescents with menstrual pain have an interest in using a mindfulness app for pain but have unique needs that need to be addressed to ensure app engagement and relevance for this population. Concrete recommendations for future app development are provided.

Deep Infiltrating Endometriosis in Adolescence: Early Diagnosis and Possible Prevention of Disease Progression

Endometriosis has a prevalence of 10% worldwide in premenopausal women. Probably, endometriosis begins early in the life of young girls, and it is commonly diagnosed later in life. The prevalence of deep infiltrating endometriosis (DIE) in adolescence is currently unknown due to diagnostic limits and underestimation of clinical symptoms. Dysmenorrhea is a common symptom in adolescents affected by DIE, often accompanied by dyspareunia and chronic acyclic pelvic pain. Ultrasonography-either performed transabdominal, transvaginal or transrectal-should be considered the first-line imaging technique despite the potential for missed diagnosis due to early-stage disease. Magnetic resonance imaging should be preferred in the case of virgo patients or when ultrasonographic exam is not accepted. Diagnostic laparoscopy is deemed acceptable in the case of suspected DIE not responding to conventional hormonal therapy. An early medical and/or surgical treatment may reduce disease progression with an immediate improvement in quality of life and fertility, but at the same time, painful symptoms may persist or even recur due to the surgery itself. The aim of this narrative review is to report the prevalence of DIE in adolescents, describe the pathogenetic theories and discuss the management in adolescent women, including the challenging road to diagnosis and the treatment alternatives.

Development and initial validation of the menstrual sensitivity index

OBJECTIVE

The present study sought to develop and perform the initial validation of a scale assessing sensitivity to menstrual pain and symptoms.

METHODS

Data were taken from a larger parent study in which participants were recruited from a nationwide sample of individuals via the UniVox platform (www.univoxcommunity.com). In that study, participants were stratified by age and self-reported menstrual pain. Participants in the parent study completed 2 online surveys, one at baseline and one at a 3-month follow up. Participants who provided complete responses to the potential scale items, as well as a variety of validated questionnaires, were included in the present analyses. Final item selection was determined by factor analyses, and measures of validity and reliability were examined.

RESULTS

Factor analyses support an 8-item scale assessing menstrual sensitivity. This scale, the Menstrual Sensitivity Index, demonstrates excellent internal consistency, good item-total correlations, and good total score test-retest reliability. Convergent validity emerged for menstrual- and pain-specific measures, and divergent validity emerged for anxiety sensitivity, anxiety, depression, nonmenstrual bodily pain, and premenstrual symptoms.

CONCLUSIONS

Menstrual sensitivity is a unique construct that reflects women's attunement to and fear of menstrual symptoms, and the Menstrual Sensitivity Index is a valid and reliable measure of this construct. This scale could be useful in advancing research and clinical work targeting menstrual pain.

Guideline No. 445: Management of Chronic Pelvic Pain

OBJECTIVE

To provide evidence-based recommendations for the management of chronic pelvic pain in females.

TARGET POPULATION

This guideline is specific to pelvic pain in adolescent and adult females and excluded literature that looked at pelvic pain in males. It also did not address genital pain.

BENEFITS, HARMS, AND COSTS

The intent is to benefit patients with chronic pelvic pain by providing an evidence-based approach to management. Access to certain interventions such as physiotherapy and psychological treatments, and to interdisciplinary care overall, may be limited by costs and service availability.

EVIDENCE

Medline and the Cochrane Database from 1990 to 2020 were searched for articles in English on subjects related to chronic pelvic pain, including diagnosis, overlapping pain conditions, central sensitization, management, medications, surgery, physiotherapy, psychological therapies, alternative and complementary therapies, and multidisciplinary and interdisciplinary care. The committee reviewed the literature and available data and used a consensus approach to develop recommendations. Only articles in English and pertaining to female subjects were included.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Family physicians, gynaecologists, urologists, pain specialists, physiotherapists, and mental health professionals.

TWEETABLE ABSTRACT

Management of chronic pelvic pain should consider multifactorial contributors, including underlying central sensitization/nociplastic pain, and employ an interdisciplinary biopsychosocial approach that includes pain education, physiotherapy, and psychological & medical treatments.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Peony Pollen Protects against Primary Dysmenorrhea in Mice by Inhibiting Inflammatory Response and Regulating the COX2/PGE2 Pathway

Peony pollen contains multiple nutrients and components and has been used as a traditional Chinese medicine with a long history, but the effect of the treatment of primary dysmenorrhea remains to be clarified. The aim of this study is to investigate the therapeutic effect of peony pollen on primary dysmenorrhea mice and the potential mechanism. A uterus contraction model in vitro and primary dysmenorrhea mice were used to evaluate the treatment effect of peony pollen on primary dysmenorrhea. The primary dysmenorrhea mice were treated with 62.5 mg/kg, 125 mg/kg, or 250 mg/kg of peony pollen, and the writhing response, latency period, histopathological changes in the uterus, prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) levels, and infiltration of neutrophils and macrophages were investigated. Protein expression of interleukin 1 β (IL-1β), interleukin 6 (IL-6), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), cyclooxygenase-2 (COX-2), microsomal prostaglandin-E synthase 1 (mPGEs-1), BCL2-Associated X (Bax), B-cell lymphoma-2 (BCL-2), caspase-3, and cleaved caspase-3 were detected by Western blot, and the oxidative stress related marker malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and reactive oxygen species (ROS) were evaluated. Peony pollen could attenuate spontaneous or oxytocin-induced uterus contractions in vitro. Moreover, peony pollen decreased the writhing times, prolonged the writhing latency, and reduced the pathological damage of uterine tissues. Furthermore, the inflammatory cell infiltration and the protein expression of IL-1β, IL-6, and NLRP3 were decreased. The COX-2/PGE2 pathway was inhibited; oxidative stress and apoptosis in the uterus also improved in the uterus of primary dysmenorrhea mice. Peony pollen exerts a positive effect on primary dysmenorrhea by inhibiting the inflammatory response and modulating oxidative stress and apoptosis by regulating the COX-2/PGE2 pathway.

Dysmenorrhea and psychological distress: a meta-analysis

Dysmenorrhea is characterized by pelvic pain associated with menstruation. Similar to people with other pain conditions, females who experience dysmenorrhea report increased psychological distress. However, the pooled magnitude of this association has not been quantified across studies. Accordingly, this meta-analytic review quantifies the magnitude of the associations between dysmenorrhea severity and psychological distress. We conducted a systematic search of the literature using PsycINFO, PubMed, CINHAL, Embase, and Web of Science. Analyzed studies provided observational data on dysmenorrhea severity and anxiety symptoms, depressive symptoms, and/or global psychological distress. A total of 44 studies were included, and three random-effects meta-analyses were conducted, with average pooled effect sizes calculated using Person's r. We found significant, positive associations between measures of dysmenorrhea severity and measures of depressive symptoms (r = 0.216), anxiety symptoms (r = 0.207), and global psychological distress (r = 0.311). Our review suggests that females with greater dysmenorrhea severity experience greater psychological distress. Future directions include defining a clinically meaningful dysmenorrhea severity threshold, understanding the mechanisms and directionality underlying the dysmenorrhea-psychological distress relationship, and designing and testing interventions to jointly address dysmenorrhea and psychological distress.

[Holistic treatment of endometriosis]

BACKGROUND

The pain phenomena caused by endometriosis are manifold. In addition to nociceptive pain there is also a nociplastic reaction with central sensitization. Atypical symptoms, such as acyclic lower abdominal pain, radiating pain, nonspecific bladder and intestinal complaints or even depression increasingly occur in addition to the classical cyclic complaints, such as severe dysmenorrhea, cyclic lower abdominal pain, dyspareunia, dysuria and dyschezia. Due to the diffuse range of symptoms, affected patients often consult not just gynecologists but also specialists from other disciplines (internal medicine, gastroenterology, orthopedics, pain therapy, psychology etc.).

OBJECTIVE

The complexity of endometriosis is presented. The resulting approaches to multimodal interdisciplinary holistic treatment are described.

RESULTS

Interdisciplinary concepts should be involved in the optimal treatment of endometriosis patients along with hormonal and surgical treatment, mostly under the supervision of a gynecologist and pain management, dietary changes, psychological support and physiotherapeutic management should also be included. This article provides an overview of possible treatment strategies for chronic symptomatic endometriosis.

CONCLUSION

Based on multimodal treatment strategies and regarding the complex pathophysiological alterations of this disease, the complex complaints that significantly impair the quality of life of endometriosis patients can be greatly improved.

Women's experiences of primary dysmenorrhea symptoms: a systematic review of qualitative evidence and meta-aggregation

Primary dysmenorrhea (PD) has a significant impact on women's lives, especially among young women who miss school and work due to painful periods. Experiences and how women manage PD have been explored to some extent, but the evidence has not been systematically collated and reviewed to allow health professionals to better understand women's experiences of and perceptions about PD. Hence, we aim to synthesize the qualitative evidence related to women's experiences of PD and associated symptoms. For this purpose, seven databases (Ovid MEDLINE®, PubMed, Embase, APA PsycINFO, Web of Science, CINAHL and OpenGrey) were searched for relevant papers published in English, Spanish, Greek and Chinese between January 1997 and May 2021. All studies investigating women's experiences with PD were included; besides, The Critical Appraisal Skills Programme (CASP) tool for qualitative studies was used to critically appraise the papers. A data extraction form was developed using JBI template and findings from the papers were analyzed and synthesized using meta-aggregation. Sixteen articles were included and during the analysis five themes were identified: Experiencing pain and associated symptoms, the psychological dimension of PD, knowledge and support, day-to-day living with PD, and coping strategies. We concluded taboos and deeply rooted beliefs around menstruation can potentially lead to gender inequalities; hence, women's common concerns and their experiences with PD need to be considered. Training and treatment protocols for health practitioners are needed. Future research should focus on development and testing of protocols for diagnosis, pharmacological and non-pharmacological management and men's perceptions of menstruation of their lovers.

Multimodal hypersensitivity derived from quantitative sensory testing predicts pelvic pain outcome: an observational cohort study

ABSTRACT

Multimodal hypersensitivity (MMH)-greater sensitivity across multiple sensory modalities (eg, light, sound, temperature, pressure)-is associated with the development of chronic pain. However, previous MMH studies are restricted given their reliance on self-reported questionnaires, narrow use of multimodal sensory testing, or limited follow-up. We conducted multimodal sensory testing on an observational cohort of 200 reproductive-aged women, including those at elevated risk for chronic pelvic pain conditions and pain-free controls. Multimodal sensory testing included visual, auditory, and bodily pressure, pelvic pressure, thermal, and bladder pain testing. Self-reported pelvic pain was examined over 4 years. A principal component analysis of sensory testing measures resulted in 3 orthogonal factors that explained 43% of the variance: MMH, pressure pain stimulus response, and bladder hypersensitivity. The MMH and bladder hypersensitivity factors correlated with baseline self-reported menstrual pain, genitourinary symptoms, depression, anxiety, and health. Over time, MMH increasingly predicted pelvic pain and was the only component to predict outcome 4 years later, even when adjusted for baseline pelvic pain. Multimodal hypersensitivity was a better predictor of pelvic pain outcome than a questionnaire-based assessment of generalized sensory sensitivity. These results suggest that MMHs overarching neural mechanisms convey more substantial long-term risk for pelvic pain than variation in individual sensory modalities. Further research on the modifiability of MMH could inform future treatment developments in chronic pain.

Disease Burden of Dysmenorrhea: Impact on Life Course Potential

Dysmenorrhea is the most common gynecologic condition among the female population and has a significant impact on life course potential. It has a widespread impact on a female's mental and physical well-being, with longstanding impairments on quality of life, personal relationships, and education and career attainment. Furthermore, untreated dysmenorrhea can lead to hyperalgesic priming, which predisposes to chronic pelvic pain. Primary dysmenorrhea is pain in the lower abdomen that occurs before or during menses and in the absence of pelvic pathology. One possible mechanism is endometrial inflammation and increased prostaglandin release, resulting in painful uterine contractions. Dysmenorrhea may also occur secondary to pelvic pathology, such as endometriosis, adenomyosis or due to cyclic exacerbation of non-gynecologic pain conditions. A thorough patient evaluation is essential to differentiate between potential causes and guide management. Treatment must be tailored to individual patient symptoms. Pharmacologic management with non-steroidal anti-inflammatory medications and/or combined hormonal contraceptives is most common. Heat therapy, exercise, vitamins and dietary supplements have limited evidence and can be offered for patients seeking non-pharmacologic adjunctive or alternative options. Greater awareness for both health-care providers and patients allows for early intervention to reduce impact on quality of life and life course potential.

Endometriosis-associated chronic pelvic pain

Endometriosis is a heterogeneous disease where neurogenic sensitization can lead to chronic pain within and beyond the pelvis. Coincident pain and comorbidities merit specific attention. We discuss the causes, comorbidities, and management of endometriosis-associated chronic pelvic pain, advocating for a multidisciplinary approach to develop more effective treatments.

Dysmenorrhea catastrophizing and functional impairment in female pelvic pain

Background

Dysmenorrhea is suggested to increase the risk of chronic pain by enhancing central sensitization. However, little is known about whether emotional and cognitive responses induced by dysmenorrhea contribute to chronic pain interference. This study examined the association between catastrophizing specific to dysmenorrhea and both dysmenorrhea and chronic pelvic pain (CPP)-associated pain interference.

Methods

Women (N = 104) receiving care for CPP through a tertiary gynecological pain clinic between 2017 and 2020 were recruited. They completed the Pain Catastrophizing Scale, the Brief Pain Inventory-pain interference, and a separate questionnaire regarding dysmenorrhea symptoms and treatment preceding the development of CPP. Dysmenorrhea catastrophizing and interference measures were developed and tested for internal consistency and construct validity. Multiple linear regression models examined dysmenorrhea catastrophizing in association with dysmenorrhea interference and CPP-associated pain interference.

Results

Dysmenorrhea catastrophizing and interference measures demonstrated excellent internal consistency (Cronbach's Alpha = 0.93 and 0.92 respectively) and evidence of construct validity (correlated with dysmenorrhea severity and treatment, Ps < 0.01). Dysmenorrhea catastrophizing was moderately correlated with pain catastrophizing (ρ = 0.30, P = 0.003), and was associated with greater dysmenorrhea interference (P < 0.001) and CPP-associated pain interference (P = 0.032) accounting for general pain catastrophizing and other outcome-specific confounders. Dysmenorrhea intensity was most predictive of dysmenorrhea catastrophizing.

Conclusion

Among our clinical sample of women with CPP, dysmenorrhea catastrophizing was associated with greater dysmenorrhea interference and subsequent CPP-associated pain interference. More research is needed to determine whether reduction in dysmenorrhea catastrophizing leads to reduced pain interference associated with female pelvic pain.

The role of catastrophizing in chronic cyclical pelvic pain: A systematic review and meta-analysis

BACKGROUND

Dysmenorrhea (painful menstrual cramps) is one of the most common gynecological complaints in women and girls. Dysmenorrhea may be a condition itself or a result of another medical condition, including endometriosis and chronic pelvic pain. Research examining the relationship between menstrual pain ratings and catastrophizing has produced mixed results.

OBJECTIVE

To review and meta-analyze the relationship between catastrophizing and pain ratings of chronic cyclical pelvic pain.

DESIGN

Cross-sectional, longitudinal, and intervention studies that reported the relationship between menstrual/pelvic pain and catastrophizing were included. Study populations had to include healthy menstruating persons or persons with a condition associated with cyclical pelvic pain including primary dysmenorrhea, endometriosis, and/or chronic pelvic pain.

DATA SOURCES AND METHODS

A systematic search of articles published since 2012 on PubMed, PsychInfo, CINHAL, and Medline was conducted in January and rerun in November of 2022. Search terms included cyclical pelvic pain, dysmenorrhea, endometriosis, pelvic pain, and catastrophizing. Data extraction was completed independently by two extractors and cross-checked for errors. A random-effects meta-regression was used to synthesize the data using restricted maximum likelihood.

RESULTS

Twenty-five studies examining 4,540 participants were included. A random effects model found a meta-correlation between catastrophizing and pain of r = .31 (95% confidence interval: .23-.40) p < .001. Heterogeneity was large and significant (I2 = 84.5%, Q(24) = 155.16, p < .001). Studies that measured general pelvic pain rather than cyclical pelvic pain specifically and those that used multi-item rather than single-item measures of pain had significantly higher correlations. Age and depression did not moderate the relationship between catastrophizing and pain.

CONCLUSION

A systematic review and meta-analysis found that catastrophizing had a small but significant positive association with pain ratings. Patients experiencing cyclical pelvic pain may benefit from interventions targeting the psychological management of pain.

REGISTRATION

This meta-analysis was registered in PROSPERO on 14 January 2022. Registration number: CRD42022295328.

Generalized sensory sensitivity is associated with comorbid pain symptoms: a replication study in women with dysmenorrhea

ABSTRACT

Dysmenorrhea is characterized by high rates of transition to chronic pain. In a previous study using structural equation modeling, we demonstrated that several symptom domains associated with the emerging concept of nociplastic pain can be described using 2 symptom groups: generalized sensory sensitivity (GSS; composed of widespread pain, interceptive sensitivity, and environmental sensitivity) and SPACE (composed of unrefreshing sleep, pain, affective disturbances, cognitive issues, and reduced energy). Here, we perform a secondary cross-sectional analysis examining the same symptoms groups in a cohort of patients with dysmenorrhea without a diagnosis of chronic pain. Our purpose is to determine if the same symptom patterns are apparent and if they are associated with the presence and severity of comorbid pain. Participants were 201 women with dysmenorrhea. We replicated the hypothesized 2-factor structure in this cohort (comparative fit index = 0.971 and root mean square error of approximation =0.055; 90% CI: 0.000-0.097). Generalized sensory sensitivity was associated with the severity of bladder, bowel, and overall pain in multivariable models including SPACE, patient age, and BMI (all β > 0.32, all P < 0.05). Sleep, pain, affective disturbances, cognitive issues, and reduced energy were associated with menstrual pain during nonsteroidal anti-inflammatory drug use, whereas GSS was associated with the same in the absence of nonsteroidal anti-inflammatory drug use (both P < 0.05). This 2-factor model of symptoms seems to be replicable and valid in a cohort of women at risk for developing chronic pain conditions. These symptom groups are promising potential markers of future pain chronification and may point to patients in need of earlier or more aggressive intervention.

Relationship between somatic symptoms with menstruation and intention to leave work among university hospital nurses in Japan: a cross-sectional study

PURPOSE

This study investigated the association between menstrual symptoms and the intention to leave work among female nurses in Japan.

METHODS

This cross-sectional study investigated female nurses (n = 317) at two university hospitals. The items measured were their characteristics (e.g., age, body mass index), "intention to leave" work, somatic symptoms related with menstruation, self-reported menstrual characteristics (e.g., pain), physical workloads (e.g., working hours and night shifts) and psychological workloads, measured with the Copenhagen Burnout Inventory (CBI), and the Job Content Questionnaire (JCQ). Participants with at least four somatic symptoms (e.g., cold, fatigue) which are present during their menstrual cycles were considered to have "somatic symptoms associated with menstruation." We also measured serum ovarian and gonadotropin-releasing hormones.

RESULTS

Approximately 40% of women answered "intention to leave" work, and 17% had "somatic symptoms associated with menstruation." Multiple logistic regression analysis suggested that nurses reporting "somatic symptoms associated with menstruation" were more likely to have "intention to leave" work: the adjusted odds ratios (AOR, 95% confidence interval [CI]) were 2.15 (1.12-4.11) in the personal-burnout model, 2.23 (1.16-4.31) in the work-related burnout model, 2.91 (1.52-5.56) in the client-related burnout model; 2.96 (1.50-5.82) in the JCQ model. There was no association between serum and gonadotropin hormones and the intention to leave.

CONCLUSION

Somatic symptoms with menstruation were associated with intention to leave work among female Japanese nurses. Intervention for somatic symptoms with menstruation might support nurses to continue work.

Association between pelvic pain bothersomeness and pain sensitivity: A community-based cross-sectional study of young adult females in the Raine Study

OBJECTIVE

Pelvic pain has been associated with augmented nociceptive processing, but large studies controlling for multiple potential confounding factors are lacking. This study investigated the association between pelvic pain bothersomeness and pain sensitivity in young adult women, accounting for potential confounding factors.

DESIGN

Cross-sectional study.

SETTING

Community-dwelling sample.

POPULATION

The Raine Study Gen2-22 year follow-up (n = 475).

MAIN OUTCOME MEASURES

The experience of bothersomeness related to pelvic pain was determined from a question in the Urogenital Distress Inventory short form. Pain sensitivity was measured using pressure pain and cold pain thresholds. Potential confounding factors included ethnicity, marital status, highest level of education, income, waist-hip ratio, level of activity, sleep quality, smoking, comorbidity history, C-reactive protein level, musculoskeletal pain experience and psychological distress.

RESULTS

Three hundred and sixty-two women (76.2%) reported no pelvic pain bothersomeness, 74 (15.6%) reported mild pelvic pain bothersomeness and 39 (8.2%) reported moderate-severe pelvic pain bothersomeness. After adjusting for marital status (and test site), moderate-severe pelvic pain bothersomeness was associated with a lower pressure pain threshold (i.e. greater pressure pain sensitivity) (coefficient -51.46, 95% CI -98.06 to -4.86, p = 0.030). After adjusting for smoking, moderate-severe pelvic pain bothersomeness was also associated with a higher cold pain threshold (i.e. greater cold pain sensitivity) (coefficient 4.35, 95% CI 0.90-7.79, p = 0.014).

CONCLUSIONS

This study suggests augmented nociceptive processing as a contributing factor in pelvic pain bothersomeness for some women. Thorough assessment of women who present clinically with pelvic pain should consider pain sensitivity as a potential contributing factor to their presentation.

The progestin-only pills drospirenone 4 mg and desogestrel 0.075 mg as an option for the management of dysmenorrhea and mastodynia

INTRODUCTION

Dysmenorrhea and mastodynia are the most common gynecologic pain causes in women of all ages and races during their reproductive life. The following study aimed to show the influence of two POP´s in the development of dysmenorrhea and mastodynia after nine months of use.

MATERIAL AND METHODS

A total of 858 women with 6691 drospirenone (DRSP) cycles and 332 women with 2487 desogestrel (DSG) cycles were analyzed. Women included in this study were all child-bearing potentials, at risk of pregnancy, agreeing to use only the study medication for contraception for the duration of the study medication treatment, aged 18 to 45.

RESULTS

At screening, 168 (19.6%) of the 858 patients using DRSP and 64 (19,3%) of the DSG patients reported that they had suffered from dysmenorrhea within six cycles prior to the first visit before starting with the medication. 20,2% of the DRSP and 10,9% of the DSG group had a sever dysmenorrhea. After 9 cycles this was reduced to 0,6% and 3,1% respectively. In total, 96 women (11.2%) in the DRSP and 49 (14,8%) experienced mastodynia within six cycles before the screening. Of these 91.6% in the DRSP group and 91,8% in the DSG group had no or mild mastodynoa at follow-up.

DISCUSSION

The progestins 4 mg and desogestrel 0,075 mg showed a marked effect in the non-contraceptive aspects of dysmenorrhea and mastodynia so that new possibilities are opened for these two benign gynecological diseases. Future studies must reaffirm these first data.

Coping with dysmenorrhea: a qualitative analysis of period pain management among students who menstruate

BACKGROUND

Dysmenorrhea, or period pain, affects up to 95% of menstruating individuals and is a common cause of educational absenteeism among students who menstruate worldwide. Evidence suggests that students may lack sufficient knowledge about their menstrual health, which may impede self-management. The aim of the current study was to explore pain management strategies used by students in Ireland with painful periods and to identify their unaddressed needs across physical, psychological, educational, and social domains.

METHODS

This study used a qualitative, interpretive design and opportunity sampling approach to collect and interpret individual accounts of dysmenorrhea from third-level students in Ireland. Data from 21 students were collected using semi-structured online one-to-one interviews and analysed using reflexive thematic analysis.

RESULTS

Analysis resulted in the construction of five themes: (1) Pain management is self-directed trial-and-error, (2) Home as safe haven, (3) Prioritising productivity over pain, (4) We're missing an option between 'normalise' and 'medicalise', and (5) Cycle of censorship and concealment. Overall, limited formal education on dysmenorrhea and prevailing negative attitudes towards menstruation create an unsupportive environment for students to learn adequate coping skills. Beyond education, menstrual stigma may also restrict the availability of clear management guidance in domestic and medical spheres. Experiences of dysmenorrhea were also influenced by the COVID-19 pandemic, where work-from-home measures were viewed favourably by individuals with dysmenorrhea.

CONCLUSIONS

This study indicates that students in Ireland are inadequately prepared to cope with dysmenorrhea. The current findings have substantial implications for evaluating and reforming current menstrual education standards, in addition to clarifying the negative effects of social stigma on menstrual health literacy.

Primary dysmenorrhoea in adolescents and young women: A twin family study of maternal transmission, genetic influence and associations

AIMS

The extent to which maternal transmission of primary dysmenorrhoea is genetically determined in adolescents and young women has yet to be determined. We aimed to assess heritability and associations relevant to primary pain syndromes using a twin family study.

METHODS

Participants were young menstruating female twins, and their oldest sisters and mothers, whose families were registered with Twins Research Australia and previously participated in a twin family study of primary paediatric pain disorders. Questionnaire packs were mailed, assessing current maximum and average menstrual pain intensity, current pain interference with activities and retrospective dysmenorrhea secondary symptoms.

RESULTS

The sample comprised 206 twin individuals (57 monozygous (MZ) and 46 dizygous (DZ) pairs) aged 10-22 years, eldest siblings (n = 38) aged 13-28 years and mothers (n = 101) aged 32-61 years. The estimated regression coefficient of the relationship between mother-daughter and twin-sibling dyads indicated significant associations for the measures of dysmenorrhea and supported heritability. Adjusted for age, the within twin-pair correlation for MZ twins was generally more than twice that of DZ twins. Heritability estimates were maximal pain intensity 0.67 (P = 3.8 × 10^-11 ), average pain intensity 0.63 (P = 3.7 × 10^-10 ), pain interference 0.57 (P = 1.8 × 10^-8 ) and retrospective symptoms 0.57 (P = 1.8 × 10^-8 ). Twin individuals with a lifetime (three-month) history of iron deficiency and those with painless restless legs syndrome (RLS) were significantly more likely to have more intense pain associated with menstruation.

CONCLUSION

Primary dysmenorrhea in adolescents and young women was shown to be relatively strongly genetically influenced and associated especially with a history of iron deficiency and painless RLS which have potential therapeutic implications.

Prevalence of chronic pelvic pain and primary dysmenorrhea in women of reproductive age in Ecuador

Background

Chronic pelvic pain (CPP) and primary dysmenorrhoea are debilitating conditions that can impair the quality of life of affected women. These conditions are frequently neglected, delaying proper diagnosis and healthcare provision. This study aimed to estimate the prevalence of CPP and primary dysmenorrhoea in Ecuador and identify potential variables associated with their occurrence.

Methods

We conducted a cross-sectional survey in an urban neighbourhood of Quito, the capital of Ecuador. A total of 2397 participants of 14–49 years of age were included. The data were collected through questionnaires administered by trained interviewers.The crude and adjusted prevalence ratios were calculated using a log-binomial regression model. The correlation between pain intensity catastrophising of symptoms were statistically analysed.

Results

The prevalence of CPP and primary dysmenorrhoea was 9.8% and 8.9%, respectively. Irritative urinary symptoms, primary dysmenorrhoea, and underlying mental disorders were associated with CPP, while smoking, irritable bowel syndrome, sleep disturbance, dyspareunia, and mental disorders were associated with primary dysmenorrhoea.

Conclusions

The prevalence of CPP and primary dysmenorrhoea in Ecuador was similar to that in other Latin American countries. Primary dysmenorrhoea is a risk factor of CPP, and less than a quarter of women are undergoing treatment for the condition. Our findings reinforce the importance of healthcare interventions in anticipating the diagnosis of these conditions in women of reproductive age.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-022-01948-y.

Cortical mechanisms of visual hypersensitivity in women at risk for chronic pelvic pain

ABSTRACT

Increased sensory sensitivity across non-nociceptive modalities is a common symptom of chronic pain conditions and is associated with chronic pain development. Providing a better understanding of the brain-behavior relationships that underlie multimodal hypersensitivity (MMH) may clarify the role of MMH in the development of chronic pain. We studied sensory hypersensitivity in a cohort of women (n = 147) who had diary confirmation of menstrual status and were enriched with risk factors for chronic pelvic pain, such as dysmenorrhea and increased bladder sensitivity. We administered 2 experimental tasks to evaluate the cross-modal relationship between visual and visceral sensitivity. Visual sensitivity was probed by presenting participants with a periodic pattern-reversal checkerboard stimulus presented across 5 brightness intensities during electroencephalography recording. Self-reported visual unpleasantness ratings for each brightness intensity were simultaneously assessed. Visceral sensitivity was evaluated with an experimental bladder-filling task associated with early clinical symptoms of chronic pelvic pain. Visually evoked cortical activity increased with brightness intensity across the entire scalp, especially at occipital electrode sites. Visual stimulation-induced unpleasantness was associated with provoked bladder pain and evoked primary visual cortex activity. However, the relationship between unpleasantness and cortical activity was moderated by provoked bladder pain. These results demonstrate that activity in the primary visual cortex is not greater in individuals with greater visceral sensitivity. We hypothesize that downstream interpretation or integration of this signal is amplified in individuals with visceral hypersensitivity. Future studies aimed at reducing MMH in chronic pain conditions should prioritize targeting of cortical mechanisms responsible for aberrant downstream sensory integration.

Depression, Anxiety, and Self-Directed Violence in Women With Endometriosis: A Retrospective Matched-Cohort Study

The purpose of this study was to compare the incidence of mental health outcomes in women in the United States with and without documented endometriosis. In a retrospective matched-cohort study using administrative health claims data from Optum's Clinformatics DataMart from May 1, 2000, through March 31, 2019, women aged 18-50 years with endometriosis (n = 72,677), identified by International Classification of Disease diagnosis codes (revisions 9 or 10), were matched 1:2 on age and calendar time to women without endometriosis (n = 147,251), with a median follow-up of 529 days (interquartile range, 195, 1,164). The rate per 1,000 person-years of anxiety, depression, and self-directed violence among women with endometriosis was 57.1, 47.7, and 0.9, respectively. Comparing women with endometriosis to those without, the adjusted hazard ratios and 95% confidence intervals were 1.38 (1.34, 1.42) for anxiety, 1.48 (1.44, 1.53) for depression, and 2.03 (1.60, 2.58) for self-directed violence. The association with depression was stronger among women younger than 35 years (P for heterogeneity < 0.01). Risk factors for incident depression, anxiety, and self-directed violence among women with endometriosis included endometriosis-related pain symptoms and prevalence of other chronic conditions associated with pain. The identification of risk factors for mental health conditions among women with endometriosis may improve patient-centered disease management.

Is primary dysmenorrhea a precursor of future endometriosis development?

Primary dysmenorrhea (PD) is the most common gynecologic disorder during adolescence and it is characterized by crampy lower abdominal pain that occurs during menstruation. Secondary dysmenorrhea, in contrast, has the same clinical features but occurs in women with a disease that could account for their symptoms (endometriosis, adenomyosis, uterine fibroids, pelvic inflammatory disease). Endometriosis is the most common cause of secondary dysmenorrhea and it should be considered in patients with persistent and clinically significant dysmenorrhea despite treatment. It is often diagnosed after a long delay, increasing the likelihood of pain chronicity and fertility problems at a later age. Women who suffer from dysmenorrhea in adolescence have higher risk of endometriosis in future. The open question is if endometriosis was already present at the onset of dysmenorrhea but undiagnosed or if PD favors subsequent development of endometriosis-associated pain. Since PD is associated with higher risk for developing chronic pain state and shares some of the same pain pathways of endometriosis (prostaglandins overproduction, inflammation, peripheral sensitization, central sensitization and abnormal stress responses), a correlation between PD and endometriosis is suggested. To know whether it is a risk factor for the development of endometriosis-associated pain may provide an opportunity for early intervention and prevention. The present review aims to investigate the clinical and pathogenetic features of PD and endometriosis in order to identify a possible association between the two conditions.

Prospective Association between Dysmenorrhea and Chronic Pain Development in Community-Dwelling Women

Despite emerging evidence of associations between dysmenorrhea, enhanced pain sensitivity, and functional neuroimaging patterns consistent with chronic pain, it is unknown whether dysmenorrhea is prospectively associated with chronic pain development. Gaining a better understanding of this relationship could inform efforts in prevention of chronic pain. Using data from the national Midlife in the United States cohort, we examined the prospective association between dysmenorrhea and chronic pain development during a 10-year follow-up (starting 10 years after dysmenorrhea was measured) among 874 community-dwelling women aged 25-74 at baseline (when dysmenorrhea was measured). We fit modified Poisson regression models adjusting for sociodemographic, lifestyle and psychosocial factors. Among women who were menstruating at baseline, self-reported dysmenorrhea was associated with a 41% greater (95% confidence interval [CI] = 6%-88%) risk of developing chronic pain. Women with dysmenorrhea also developed chronic pain in more body regions (≥3 regions vs 1-2 regions vs none, odds ratio [OR] = 1.77, 95% CI = 1.18-2.64) and experienced greater pain interference (high-interference vs low-interference vs none, OR = 1.73, 95% CI = 1.15-2.59). Among women who had stopped menstruation at baseline, we did not find evidence of an association between their history of dysmenorrhea and subsequent risk of chronic pain development. Results suggest dysmenorrhea may be a general risk factor for chronic pain development among menstruating women. PERSPECTIVE: This study supports the temporality of dysmenorrhea and chronic pain development in a national female sample. Dysmenorrhea was also associated with developing more widespread and disabling pain among women who were still menstruating. Early management of dysmenorrhea may reduce the development and severity of chronic pain in women, although further research is required to determine whether dysmenorrhea is a causal risk factor or a risk marker of chronic pain.

Current Resources for Evidence-Based Practice, March 2021

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of men's experiences of pregnancy loss and commentaries on reviews focused on the effects of perineal massage on perineal trauma and air pollution and heat exposure on birth outcomes.

Ecological Momentary Assessment of Non-Menstrual Pelvic Pain: Potential Pathways of Central Sensitization in Adolescents and Young Adults with and without Primary Dysmenorrhea

Purpose

Primary dysmenorrhea (PD; menstrual pain without an identified organic cause) has been proposed as a possible risk factor for the development of chronic pelvic pain, but the mechanism through which this process occurs is unknown. One possible mechanism is central sensitization – alterations in the central nervous system that increase responsiveness to pain leading to hypersensitivity. Repeated episodes of pain, such as those experienced over time with PD, may alter how the brain processes pain. Ecological momentary assessment (EMA; collection of data in real time in participants’ natural environments) is a novel data collection method that may help elucidate pain occurring during non-menstrual cycle phases.

Patients and Methods

The current observational study assessed the feasibility and acceptability of using EMA via text messages to collect pelvic pain data during menstrual and non-menstrual cycle phases in a community sample of adolescents and young adults (AYA) aged 16–24 years with and without PD and explored occurrence rates and intensity of non-menstrual pelvic pain (NMPP) in each of these groups.

Results

Thirty-nine AYA with PD and 53 healthy controls reported pelvic pain level via nightly text message. Global response rate was 98.5%, and all participants reported that the EMA protocol was acceptable. AYA with PD reported higher intensity (2.0 vs 1.6 on 0–10 numeric rating scale; p=0.003) and frequency (8.7% vs 3.1% of days; p=0.004) of NMPP compared to healthy controls.

Conclusion

The EMA protocol was feasible and acceptable. Though both the intensity and frequency of NMPP were low and at levels that would not typically warrant clinical assessment or intervention, these repeated nociceptive events may represent a potential mechanism contributing to the transition from cyclical to chronic pelvic pain in some individuals.

Hormonal Contraceptive Treatment May Reduce the Risk of Fibromyalgia in Women with Dysmenorrhea: A Cohort Study

Dysmenorrhea is the most common gynecological disorder for women in the reproductive age. Study has indicated that dysmenorrhea might be a general risk factor of chronic pelvic pain and even chronic non-pelvic pain, such as fibromyalgia. We used the Longitudinal Health Insurance Database 2000 from the Taiwan National Health Research Institutes Database to investigate whether women with dysmenorrhea have a higher risk of fibromyalgia and whether treatment of dysmenorrhea reduced the risk of fibromyalgia. The dysmenorrhea cohort was matched with a non-dysmenorrhea cohort at a 1:1 ratio based on gender, age, and the year of entry study by frequency matching. Multivariable Cox proportional hazard regression models were used to assess the risk of fibromyalgia, with controlling for potential confounding variables such as age, comorbidities, and medication use. After controlling confounding variables, results revealed that women with dysmenorrhea have a significantly higher risk of fibromyalgia than women without dysmenorrhea. However, only treatment of dysmenorrhea with hormonal contraceptives reduce the risk of fibromyalgia. These results indicated that dysmenorrhea may be a risk factor of fibromyalgia, whereas personalized medicine for treatment of dysmenorrhea may be the key to reduce the risk of fibromyalgia. Future studies are needed to identify the causes and prevention strategies in detail.

Phenotypes of Women with and Without Endometriosis and Relationship with Functional Pain Disability

Objective

Primary dysmenorrhea and secondary dysmenorrhea due to endometriosis share overlapping symptoms and likely demonstrate aspects of central sensitization. The present study aimed to identify distinct phenotypes of women who have dysmenorrhea with and without endometriosis to shed light on the unique mechanisms contributing to the pathogenesis of each condition.

Methods

An online survey was used to investigate the relationship between ratings of menstrual pain severity, menstrual symptoms (abdominal cramps, abdominal discomfort, low back pain, headache, body aches, bloating, nausea, diarrhea, increased bowel movements), widespread pain, and functional pain disability in a community sample of 1,354 women (aged 18–50) with menstrual pain in Australia.

Results

Compared with women without endometriosis, those with endometriosis had statistically significant higher menstrual pain severity (P&lt;0.01), symptom severity and fatigue (all symptoms P&lt;0.001, although only cramps and bloating were clinically significant), widespread pain sites (P&lt;0.001), and functional pain disability (P&lt;0.001, although this difference was not clinically significant). When examining symptoms by pain severity, women with severe menstrual pain were more likely to experience symptoms than women with less severe pain, regardless of the presence of endometriosis. Similar predictors of functional pain disability emerged for women with and without endometriosis, such as body aches, nausea, fatigue, and widespread pain, respectively, suggesting the presence of central sensitization in both groups. Logistic regression revealed that after accounting for menstrual pain severity (odds ratio [OR], 1.61) and duration (OR, 1.04), symptoms of bloating (OR, 1.12), nausea (OR, 1.07), and widespread pain sites (OR, 1.06) significantly predicted the presence of endometriosis.

Conclusions

The findings suggest that phenotypes specific to endometriosis can be identified.

The effect of endometriosis on sexual function as assessed with the Female Sexual Function Index: systematic review and meta-analysis

AIM

To systematically compare sexual function between non-treated women with and without endometriosis.

METHODS

A systematic review was performed on PubMed/Medline, Scopus, EMBASE, Web of Science and Cochrane Library databases searching studies that analyzed sexual function (assessed with the 19-item Female Sexual Function Index [FSFI]), and dyspareunia, chronic pelvic pain and dysmenorrhea (assessed with a visual analogue scale [VAS]) in women with and with endometriosis.

RESULTS

In 4 studies, non-treated women with endometriosis presented a higher risk of female sexual dysfunction (mean total FSFI score ≤ 26.55; OR = 2.38; 95% confidence interval [CI] = 1.12, 5.04). Although mean total FSFI scores were not significantly different between women with and without endometriosis (mean difference [MD] = -2.15; 95% CI -4.96, 0.67); all FSFI domain scores were significantly lower in women with endometriosis (n = 4 studies): desire (MD = -0.43; 95% CI -0.57, -0.19); arousal (MD = -0.66; 95% CI -1.15, -0.17); lubrication (MD = -0.41; 95% CI -0.79, -0.02); orgasm (MD = -0.40; 95% CI -0.73, -0.06); satisfaction (MD = -0.45; 95% CI -0.72, -0.18); and pain (MD = -1.03; 95% CI -1.34, -0.72). Women with endometriosis displayed differences (more severity) in terms of VAS scores (2 studies) for dyspareunia (MD = 1.88; 95% CI 0.38, 3.37) and chronic pelvic pain (MD = 2.92; 95% CI 1.26, 4.58); but not for dysmenorrhea.

CONCLUSION

Non-treated women with endometriosis displayed altered sexual function as evidenced by lower scores in all FSFI domains, and severity of dyspareunia and chronic pelvic pain.

Primary Dysmenorrhea in Relation to Oxidative Stress and Antioxidant Status: A Systematic Review of Case-Control Studies

Primary dysmenorrhea is defined as painful menstrual cramps of uterine origin in the absence of pelvic pathology and is the most common gynecological disorder among women of reproductive age. The aim of this study was to systematically review case-control studies that have investigated the oxidative stress, antioxidant status, and inflammation markers among women with primary dysmenorrhea and controls. The study protocol was registered with PROSPERO (no. CRD42020183104). By searching PubMed and Scopus databases as well as reference lists, six case-control studies with fifteen eligible markers (seven oxidative stress, seven antioxidant status, one inflammation) were included in this review. The quality of the included studies was assessed as medium or high. The systematic review included 175 women with primary dysmenorrhea and 161 controls. The results indicate an elevated level of oxidative stress, especially of lipid peroxidation among dysmenorrheal women. For the antioxidant status, limited evidence was found for a lower status among primary dysmenorrhea women, and only one study examined one inflammation marker (hs-CRP), which makes it impossible for such a conclusion. To establish whether oxidative stress, antioxidant status or inflammation participate in the pathophysiology of primary dysmenorrhea, high-quality studies with larger study groups and clear case definitions are needed.

NLRP3 inflammasome inhibitor MCC950 attenuates primary dysmenorrhea in mice via the NF-κB/COX-2/PG pathway

Background

Primary dysmenorrhea (PD) constitutes a common gynecological disease among young women. The NLRP3 inflammasome may be activated and expressed in PD, but the mechanistic link between NLRP3 inflammasome activation and PD is still unclear.

Methods

To investigate the potential role of NLRP3 inflammasome activation in the pathogenesis of PD, 30 female Kunming mice without pregnancy were used for experiments. The PD mouse model was constructed by 11 days of successive co-treatment with estradiol and oxytocin. MCC950, a potent and specific small-molecule inhibitor of the NLRP3 inflammasome, was used to treat PD mice. The disease level was assessed by the writhing response and hot water tail-flick test. The levels of prostaglandin E₂ (PGE₂) and prostaglandin F₂ alpha (PGF_2α) in the uterine tissues of mice were detected by ELISA. The expression levels of protein and cytokines, including NLRP3, cysteine aspartic acid-specific protease 1 (caspase-1), interleukin (IL)-1β, IL-18, nuclear factor kappa B (NF-κB) p65, phospho-NF-κB p65, and cyclooxygenase-2 (COX-2) were revealed by western blot analysis.

Results

MCC950 greatly ameliorated the writhing response induced by the combination of oxytocin and estradiol, with an increasing length of tail-flick latency. MCC950 also significantly decreased the levels of PGF_2α and PGE₂, and the expressions of NLRP3, caspase-1, IL-1β, IL-18, phospho-NF-κB p65, NF-κB p65, and COX-2 in the uterus.

Conclusions

MCC950 markedly alleviated the pain and pathological damage in PD mice by inhibiting NLRP3 activation. The underlying mechanism may be related to hypoactive uterine inflammation via suppression of NLRP3 activation and the NF-κB/COX-2/PG pathway in uteruses of PD mice.