Characteristics of women with endometriosis from the USA and Puerto Rico.
Fourquet, Jessica, Sinaii, Ninet, Stratton, Pamela et al. · Journal of endometriosis and pelvic pain disorders · 2015 · DOI
Quick Summary
This study compared women with endometriosis in the USA and Puerto Rico to see if their symptoms and health conditions differed. Researchers found that while both groups experienced similar types of pain and fertility problems, women in the USA reported more severe pain and more often had other chronic conditions like chronic fatigue syndrome and fibromyalgia. Women in Puerto Rico more frequently reported miscarriages.
Why It Matters
This study is relevant to ME/CFS patients because it documents high rates of chronic fatigue syndrome and fibromyalgia as comorbidities in women with endometriosis, particularly in the USA cohort. Understanding how endometriosis co-occurs with other chronic conditions like ME/CFS may help identify shared underlying mechanisms or inform integrated treatment approaches for patients with multiple concurrent illnesses.
Observed Findings
USA respondents reported significantly higher rates of chronic pelvic pain and incapacitating pain compared to Puerto Rico respondents.
Chronic fatigue syndrome and fibromyalgia were more prevalent in the USA cohort, whereas asthma was more frequent in the Puerto Rico cohort.
Miscarriages were reported more frequently by Puerto Rico participants, while USA participants more often reported infertility and heavy bleeding.
USA respondents experienced longer diagnostic delays than Puerto Rico respondents.
Both groups reported similarly high rates of endometriosis-associated pain and infertility overall.
Inferred Conclusions
Diagnostic delays in the USA may have resulted in greater symptom severity and increased prevalence of comorbidities by the time of study enrollment.
Geographic and possibly healthcare system differences between the USA and Puerto Rico influence the clinical presentation and severity of endometriosis.
Endometriosis is associated with a broad spectrum of comorbid conditions including chronic fatigue syndrome, fibromyalgia, and allergies.
Remaining Questions
What mechanisms explain the higher prevalence of chronic fatigue syndrome and fibromyalgia in the USA endometriosis cohort?
What This Study Does Not Prove
This study does not establish causality between endometriosis and comorbid conditions—it only demonstrates that they frequently co-occur. The cross-sectional design cannot determine whether diagnostic delays caused higher symptom burden or whether other factors explain the geographic differences. Self-reported diagnoses without independent clinical verification may introduce accuracy bias.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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Does earlier diagnosis in Puerto Rico actually prevent progression to more severe pain and comorbidities, or do other factors account for the differences?
Are the differences attributable to healthcare access, genetic factors, environmental exposures, or reporting biases?
Does endometriosis directly cause these comorbidities, or do shared underlying biological pathways predispose to multiple conditions?