27 papers

C Matthew Peterson

Professor, Obstetrics and Gynecology, The University of Utah

Associated Conditions · Comorbid Conditions

Endometriosis phenotypes and staging in relation to lipid biomarkers: Findings from the ENDO Cohort Study

Schliep KC et al., 2026 J Gynecol Obstet Hum Reprod Open Access

Endometriosis has been linked to cardiometabolic alterations, but whether these associations vary by disease severity or phenotype is unclear. We examined lipid profiles across endometriosis diagnosis, stage, and typology. Data came from 476 women in the NICHD ENDO cohort. Endometriosis was confirmed laparoscopically and staged using the rASRM criteria (I-IV). Typology was categorized as superficial endometriosis (SE), ovarian endometrioma (OE), deep infiltrating endometriosis (DE), and OE+DE. We compared endometriosis status, stage (I/II vs III/IV), and typology to no endometriosis using adverse lipid thresholds (total cholesterol ≥200 mg/dL, HDL <50 mg/dL, LDL ≥100 mg/dL, triglycerides ≥175 mg/dL, non-HDL ≥130 mg/dL, VLDL ≥30 mg/dL, ApoA1 <125 mg/dL, and ApoB ≥120 mg/dL). Adjusted prevalence ratios (aPR) and 95 % CIs were estimated via generalized linear models, controlling for age, race/ethnicity, BMI, income, marital status, and serum cotinine. Endometriosis diagnosis alone was not associated with adverse lipid profiles. In contrast, moderate/severe disease showed higher prevalence of elevated triglycerides (aPR= 2.27; 95 % CI: 1.18,4.35) and VLDL (aPR= 2.41; 95 % CI: 1.50, 3.85). Typology revealed stronger patterns: OE and OE+DE were associated with adverse profiles across multiple markers (aPRs 1.59-4.09), particularly ApoB and triglycerides. Minimal/mild disease and SE were not associated. The metabolic signal was phenotype-driven rather than diagnosis-driven, with severe stage and OE/OE+DE showing clear associations with adverse lipid profiles. These findings suggest lipid profiles may serve as markers of phenotype severity or shared biological milieu. Replication in larger cohorts is needed.

Diagnosis · Biomarkers

Incident endometriosis diagnosis and anti-müllerian hormone (AMH): how surgical staging and typology relate to serum AMH levels

Valenti M et al., 2026 Am J Obstet Gynecol Open Access

Endometriosis is a chronic, gynecologic condition in which tissue similar to the lining of the uterus implants throughout the body. Women with endometriosis have a higher prevalence of infertility and a greater risk of early natural menopause compared to those without endometriosis. This study aimed to evaluate preoperative serum AMH levels among women with and without incident endometriosis and to assess whether levels differ by surgical staging and typology. The ENDO (Endometriosis: Natural History, Diagnosis, and Outcomes) study was conducted between 2007 and 2009. The ENDO study consisted of an operative and population cohort (n=600). Only those in the ENDO operative cohort from the Utah site were used for this analysis, and included women aged 18 to 44 years who were scheduled for gynecologic surgery, irrespective of clinical indication (n=476). AMH levels were measured from stored serum collected before surgery using a quantitative enzyme-linked immunosorbent assay. After excluding participants with missing outcome data (n=51), unilateral oophorectomy (n=8), or those within the population cohort (n=69), 348 participants remained for the analysis. Surgically confirmed endometriosis diagnosis, staging (American Society for Reproductive Medicine I-IV), and typology (superficial, deep, ovarian) were ascertained by the operative report. Outliers for AMH (>14.0 ng/mL) were excluded from the analyses and AMH values were log-transformed. Multivariable linear regression models adjusted for age (squared and continuous), body mass index, serum cotinine levels, and exogenous hormonal contraceptive use were conducted. Percentage differences in AMH were calculated as (exp[β]-1)×100, and 95% confidence intervals were reported. Compared with no endometriosis, incident endometriosis diagnosis was associated with lower AMH levels (-19.8%; 95% confidence interval, -37.0 to 1.0); however, this association was not statistically significant. Stage III to IV disease was associated with 40.1% lower AMH levels (95% confidence interval, -58.9 to -12.7). Ovarian endometriomas were most strongly associated with lower AMH levels (-54.3%; 95% confidence interval, -69.4 to -31.8), with a more pronounced association among those with infertility (-72.6%; 95% confidence interval, -85.4 to -48.5). Deep (-24.1%; 95% confidence interval, -48.2 to 11.0) and superficial (-15.5%; 95% confidence interval, -34.6 to 9.3) endometriosis also showed a trend toward lower AMH levels, but these findings were not statistically significant. Compared with a postoperative diagnosis of a normal pelvis, incident endometriosis was associated with 26.8% lower AMH levels (95% confidence interval, -44.6 to -3.4). Stage III to IV disease was associated with 47.8% lower AMH levels (95% confidence interval, -65.8 to -23.2), and all subtypes of endometriosis were statistically significantly associated with lower levels of AMH compared with a postoperative diagnosis of a normal pelvis (ovarian: -60.8%; 95% confidence interval, -74.4 to -39.9; deep: -34.3%; 95% confidence interval, -56.2 to -1.4; superficial: -24.8%; 95% confidence interval, -43.9 to -0.8). Ovarian and moderate to severe (stage III-IV) endometriosis were associated with markedly lower AMH levels compared with no endometriosis. Compared with a postoperative diagnosis of a normal pelvis, incident endometriosis and moderate to severe stages (stage III-IV) were associated with statistically significantly lower AMH levels. Additionally, typology (deep, ovarian, or superficial) was associated with statistically significantly lower AMH levels. However, this association was likely driven by the presence of ovarian endometriomas across all subtypes. These findings are consistent with previous studies and demonstrate that endometriosis lesions themselves, independent of surgical intervention, influence AMH levels.

Environmental Exposures · Air and Water Quality

Ambient air pollution during developmental windows of spermatogenesis and semen quality among an infertility treatment seeking population

Russo LM et al., 2025 Ecotoxicol Environ Saf Open Access

Prior studies have observed impacts of air pollution on semen quality, but timing of exposure during developmental windows of spermatogenesis and impacts of low-to-moderate air pollution is less well understood. We examined the relation between air pollution and semen quality in the Folic Acid and Zinc Supplementation Trial (2013-2018), which enrolled male partners of couples seeking infertility treatment in the Salt Lake City, Utah region (n = 2015). Semen quality parameters were assessed at baseline, 2-, 4-, and 6-months follow-up. Measures of daily air pollutants at each participant's residence were abstracted from Community Multiscale Air Quality models (fine particulate matter: PM2.5, sulfur dioxide, nitrogen dioxide, and ozone: O3), linked to participants' residential addresses, and averaged across the 74-day spermatogenesis window prior to the sample collection date for each study visit, and across four developmental windows of spermatogenesis (mitosis, meiosis I-II, spermiogenesis, and spermiation). Generalized linear mixed models considered four repeated semen sample measures per participant and adjusted for co-pollutants, age, season, and income. In multi-pollutant models, O3 during early-to-mid spermatogenesis (meiosis I+II and spermiogenesis) was related to lower percent normal morphology (% difference -6.73, 95 % CI -9.82, -3.54 and % difference -3.83, 95 % CI -7.51, 0.00, respectively). Additionally, PM2.5 and O3 during late spermatogenesis (spermiation) were associated with lower count and concentration, and PM2.5 with lower progressive motility. These findings suggest that exposure to low-to-moderate levels of air pollution may negatively impact semen quality and indicate that exposure to O3 during meiosis and spermiogenesis may particularly affect normal sperm morphological development.

Fertility and Outcomes · Ovarian Reserve

Is endometriosis typology a potentially better classification system for assessing risk of female infertility?

Schliep KC et al., 2025 F S Rep Open Access

To determine whether endometriosis typology, namely ovarian endometriomas (OE), deep infiltrating endometriosis (DIE), or superficial endometriosis (SE), correlates with fertility history. Prospective cohort. One of fourteen surgical centers in Salt Lake City, Utah (n = 5) or San Francisco, California (n = 9). A total of 473 women (18-44 years) with no prior endometriosis diagnosis, undergoing laparoscopies/laparotomies, irrespective of indication, in Utah or California (2007-2009). Exposure: Incident endometriosis. Before surgery, we queried women about time to become pregnant for prior planned pregnancies. Generalized linear models were used to calculate adjusted prevalence ratios (aPR) for association between endometriosis typology and infertility, defined as having ever tried >12 months (>6 months for women ≥35 years) to get pregnant. We also generated fecundability odds ratios (aFOR) to capture time to pregnancy. Twenty-five percent (n = 116) of women were diagnosed with SE only, 5% (n = 23) with OE, 6% (n = 29) with DIE, and 5% (n = 22) with OE + DIE, and 60% (n = 283) with no endometriosis. Compared with women with no endometriosis, women with SE had a 1.58 higher aPR (95% confidence interval [CI], 1.16-2.14), although women with OE and/or DIE had a 2.41 higher aPR for subfertility after adjusting for women's age, body mass index, and site. Compared with women with no endometriosis, women with OE and/or DIE had a 53% lower historic fecundability (aFOR, 0.47; 95% CI, 0.24-0.95); however, no association was found among women with SE (aFOR, 0.81; 95% CI, 0.49-1.33). Specific endometriosis typologies may be associated with fecundability, with OE and/or DIE associated with nearly a 150% higher prevalence of subfertility and over a 50% lower historic fecundability.

Measurement and Statistics · Instrument Development and Validation

Validation of administrative health data for the identification of endometriosis diagnosis

Kiser AC et al., 2024 Hum Reprod Open Access

How do endometriosis diagnoses and subtypes reported in administrative health data compare with surgically confirmed disease? For endometriosis diagnosis, we observed substantial agreement and high sensitivity and specificity between administrative health data-International Classification of Diseases (ICD) 9 codes-and surgically confirmed diagnoses among participants who underwent gynecologic laparoscopy or laparotomy. Several studies have assessed the validity of self-reported endometriosis in comparison to medical record reporting, finding strong confirmation. We previously reported high interand intra-surgeon agreement for endometriosis diagnosis in the Endometriosis, Natural History, Diagnosis, and Outcomes (ENDO) Study. STUDY DESIGN, SIZE, In this validation study, participants (n = 412) of the Utah operative cohort of the ENDO Study (2007-2009) were linked to medical records from the Utah Population Database (UPDB) to compare endometriosis diagnoses from each source. The UPDB is a unique database containing linked data on over 11 million individuals, including statewide ambulatory and inpatient records, state vital records, and University of Utah Health and Intermountain Healthcare electronic healthcare records, capturing most Utah residents. PARTICIPANTS/MATERIALS, SETTING, The ENDO operative cohort consisted of individuals aged 18-44 years with no prior endometriosis diagnosis who underwent gynecologic laparoscopy or laparotomy for a variety of surgical indications. In total, 173 women were diagnosed with endometriosis based on surgical visualization of disease, 35% with superficial endometriosis, 9% with ovarian endometriomas, and 14% with deep infiltrating endometriosis. Contemporary administrative health data from the UPDB included ICD diagnostic codes from Utah Department of Health in-patient and ambulatory surgery records and University of Utah and Intermountain Health electronic health records. MAIN For endometriosis diagnosis, we found relatively high sensitivity (0.88) and specificity (0.87) and substantial agreement (Kappa [Κ] = 0.74). We found similarly high sensitivity, specificity, and agreement for superficial endometriosis (n = 143, 0.86, 0.83, Κ = 0.65) and ovarian endometriomas (n = 38, 0.82, 0.92, Κ = 0.58). However, deep infiltrating endometriosis (n = 58) had lower sensitivity (0.12) and agreement (Κ = 0.17), with high specificity (0.99). LIMITATIONS, Medication prescription data and unstructured data, such as clinical notes, were not included in the UPDB data used for this study. These additional data types could aid in detection of endometriosis. Most participants were white or Asian with Hispanic ethnicity reported 11% of the time, which may limit generalizability to some US states. Additionally, given that participants whose administrative health records we utilized were also part of the ENDO Study, the surgeons may have been more vigilant in diagnostic coding due to the operative forms they completed for the ENDO Study, which may have led to increased validity. However, the codes compared in the UPDB would have been entered by medical coders as part of standard clinical practice. We observed substantial agreement between administrative health data and surgically confirmed endometriosis diagnoses overall, and for superficial and ovarian endometrioma subtypes. These findings may provide reassurance to researchers using administrative healthcare records to assess risk factors and long-term health outcomes of endometriosis. Our findings corroborate prior research that demonstrates high specificity but low sensitivity for deep infiltrating endometriosis, indicating deep infiltrating endometriosis is not reliably annotated in administrative healthcare data. This suggests that medical record-based deep infiltrating endometriosis diagnoses may be suitable for etiologic studies but not for surveillance or detection studies. STUDY FUNDING/COMPETING INTEREST(S): The original ENDO Study was funded by the Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contracts NO1-DK-6-3428; NO1-DK-6-3427; 10001406-02). We acknowledge partial support for the UPDB through grant P30 CA2014 from the National Cancer Institute, University of Utah and from the University of Utah's program in Personalized Health and Center for Clinical and Translational Science. This research was also supported by the NCRR grant, 'Sharing Statewide Health Data for Genetic Research' (R01 RR021746, G. Mineau, PI) with additional support from the Utah Department of Health and Human Services, University of Utah. Additionally, this research was supported by the Utah Cancer Registry, which is funded by the National Cancer Institute's SEER Program, Contract No. HHSN261201800016I, the US Centers for Disease Control and Prevention's National Program of Cancer Registries, Cooperative Agreement No. NU58DP007131, with additional support from the University of Utah and Huntsman Cancer Foundation. Research reported in this publication was also supported by the National Institutes of Health (Award Numbers R01HL164715 [to L.V.F., K.C.S., and A.Z.P.] and K01AG058781 [to K.C.S.]), by the Huntsman Cancer Institute's Breast and Gynecologic Cancers Center, and by the Doris Duke Foundation's COVID-19 Fund to Retain Clinical Scientists funded by the American Heart Association. A.C.K. was supported by Training Grant Number 5T15LM007124 from the National Library of Medicine to K.E. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or other sponsors. There are no competing interests among any of the authors. N/A.

Gynecologic Oncology · Ovarian Cancer

Endometriosis Typology and Ovarian Cancer Risk

Barnard ME et al., 2024 JAMA Open Access

Endometriosis has been associated with an increased risk of ovarian cancer; however, the associations between endometriosis subtypes and ovarian cancer histotypes have not been well-described. To evaluate the associations of endometriosis subtypes with incidence of ovarian cancer, both overall and by histotype. DESIGN, SETTING, And Population-based cohort study using data from the Utah Population Database. The cohort was assembled by matching 78 893 women with endometriosis in a 1:5 ratio to women without endometriosis. Exposures: Endometriosis cases were identified via electronic health records and categorized as superficial endometriosis, ovarian endometriomas, deep infiltrating endometriosis, or other. Main Outcomes and Measures: Estimated adjusted hazard ratios (aHRs), adjusted risk differences (aRDs) per 10 000 women, and 95% CIs for overall ovarian cancer, type I ovarian cancer, and type II ovarian cancer comparing women with each type of endometriosis with women without endometriosis. Models accounted for sociodemographic factors, reproductive history, and past gynecologic operations. In this Utah-based cohort, the mean (SD) age at first endometriosis diagnosis was 36 (10) years. There were 597 women with ovarian cancer. Ovarian cancer risk was higher among women with endometriosis compared with women without endometriosis (aHR, 4.20 [95% CI, 3.59-4.91]; aRD, 9.90 [95% CI, 7.22-12.57]), and risk of type I ovarian cancer was especially high (aHR, 7.48 [95% CI, 5.80-9.65]; aRD, 7.53 [95% CI, 5.46-9.61]). Ovarian cancer risk was highest in women with deep infiltrating endometriosis and/or ovarian endometriomas for all ovarian cancers (aHR, 9.66 [95% CI, 7.77-12.00]; aRD, 26.71 [95% CI, 20.01-33.41]), type I ovarian cancer (aHR, 18.96 [95% CI, 13.78-26.08]; aRD, 19.57 [95% CI, 13.80-25.35]), and type II ovarian cancer (aHR, 3.72 [95% CI, 2.31-5.98]; aRD, 2.42 [95% CI, -0.01 to 4.85]). Conclusions and Relevance: Ovarian cancer risk was markedly increased among women with ovarian endometriomas and/or deep infiltrating endometriosis. This population may benefit from counseling regarding ovarian cancer risk and prevention and could be an important population for targeted screening and prevention studies.

Diagnosis · Diagnostic Delay

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

Kiser AC et al., 2024 PLoS One Open Access

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.

Associated Conditions · Comorbid Conditions

Examining the co-occurrence of endometriosis and polycystic ovarian syndrome

Schliep KC et al., 2023 AJOG Glob Rep Open Access

Polycystic ovarian syndrome and endometriosis are 2 of the most common reproductive disorders among women but are thought to be unrelated. This study aimed to examine the overlap and common symptoms of polycystic ovarian syndrome and endometriosis. The study population included the Endometriosis, Natural History, Diagnosis, and Outcomes Study (2007-2009) operative cohort: 473 women, aged 18 to 44 years, who underwent a diagnostic and/or therapeutic laparoscopy or laparotomy at 1 of 14 surgical centers located in Salt Lake City, Utah, or San Francisco, California, in addition to a population cohort composed of 127 women from the surgical centers' catchment areas. Age and site-adjusted multinomial regression models were used to estimate adjusted prevalence ratios and 95% confidence intervals of reproductive history characteristics among women with endometriosis only, women with polycystic ovarian syndrome only, and women with both endometriosis and polycystic ovarian syndrome. Among the operative cohort, 35% had endometriosis only, 9% had polycystic ovarian syndrome only, and 5% had endometriosis and polycystic ovarian syndrome. Among the population cohort, 10% had endometriosis only, 8% had polycystic ovarian syndrome only, and 2% had endometriosis and polycystic ovarian syndrome. In the operative cohort, a history of subfertility was associated with a higher adjusted probability of having both conditions (adjusted prevalence ratio, 10.33; 95% confidence interval, 3.94-27.08), followed by having endometriosis only (adjusted prevalence ratio, 2.45; 95% confidence interval, 1.56-3.84) or polycystic ovarian syndrome only (adjusted prevalence ratio, 1.15; 95% confidence interval, 0.51-2.61), than having neither condition. In addition, experiencing chronic pelvic pain within the past 12 months was associated with a higher probability of having both conditions (adjusted prevalence ratio, 2.53; 95% confidence interval, 1.07-6.00) than having neither condition. Among a cohort of women undergoing gynecologic laparoscopy or laparotomy, our study found that nearly 1 in 20 women had both an incident endometriosis diagnosis and symptoms consistent with polycystic ovarian syndrome. Among a population cohort of women not seeking gynecologic care, polycystic ovarian syndrome and endometriosis overlap prevalence was approximately 1 in 50 women.

Fertility and Outcomes · Conception After Excision

Endometriosis diagnosis, staging and typology and adverse pregnancy outcome history

Schliep KC et al., 2022 Paediatr Perinat Epidemiol

Women with endometriosis may have an increased risk of adverse pregnancy outcomes. Research has focused on infertility clinic populations limiting generalisability. Few studies report differences by endometriosis severity. We investigated the relationships between endometriosis diagnosis, staging and typology and pregnancy outcomes among an operative and population-based sample of women. Menstruating women ages 18-44 years enrolled in the ENDO Study (2007-2009), including the operative cohort: 316 gravid women undergoing laparoscopy/laparotomy at surgical centres in Utah and California; and the population cohort: 76 gravid women from the surgical centres' geographic catchment areas. Pregnancy outcomes were ascertained by questionnaire and included all pregnancies prior to study enrolment. Endometriosis was diagnosed via surgical visualisation in the operative cohort and pelvic magnetic resonance imaging in the population cohort. Adjusted prevalence ratios (aPR) and 95% confidence intervals (CI) were estimated using generalised linear mixed models for pregnancy outcomes, adjusting for women's age at study enrolment and at pregnancy, surgical site, body mass index and lifestyle factors. Women in the operative cohort with visualised endometriosis (n = 109, 34%) had a lower prevalence of live births, aPR 0.94 (95% CI 0.85, 1.03) and a higher prevalence of miscarriages, aPR 1.48 (95% CI 1.23, 1.77) compared with women without endometriosis. The direction and magnitude of estimates were similar in the population cohort. Women with deep endometriosis were 2.98-fold more likely (95% CI 1.12, 7.95) to report a miscarriage compared with women without endometriosis after adjusting for women's age at study enrolment and at pregnancy, surgical site and body mass index. No differences were seen between endometriosis staging and pregnancy outcomes. While there was no difference in number of pregnancies among women with and without endometriosis in a population-based sample, pregnancy loss was more common among women with endometriosis, notably among those with deep endometriosis.

Adiposity and Endometriosis Severity and Typology

Byun J et al., 2020 J Minim Invasive Gynecol

Prior research has collectively shown that endometriosis is inversely related to women's adiposity. The aim of this study was to assess whether this inverse relationship holds true by disease severity and typology. Cross-sectional study among women with no prior diagnosis of endometriosis. Fourteen clinical centers in Salt Lake City, UT, and San Francisco, CA. A total of 495 women (of which 473 were analyzed), aged 18-44 years, were enrolled in the operative cohort of the Endometriosis, Natural History, Diagnosis, and Outcomes (ENDO) Study. Gynecologic laparoscopy/laparotomy regardless of clinical indication. MAIN Participants underwent anthropometric assessments, body composition measurements, and evaluations of body fat distribution ratios before surgery. Surgeons completed a standardized operative report immediately after surgery to capture revised American Society for Reproductive Medicine staging (I-IV) and typology of disease (superficial endometriosis [SE], ovarian endometrioma [OE], and deep infiltrating endometriosis [DIE]). Linear mixed models, taking into account within-clinical-center correlation, were used to generate least square means (95% confidence intervals) to assess differences in adiposity measures by endometriosis stage (no endometriosis, I-IV) and typology (no endometriosis, SE, DIE, OE, OE + DIE) adjusting for age, race/ethnicity, and parity. Although most confidence intervals were wide and overlapping, 3 general impressions emerged: (1) women with incident endometriosis had the lowest anthropometric/body composition indicators compared with those without incident endometriosis, (2) women with stage I or IV endometriosis had lower indicators compared with women with stage II or III, and (3) women with OE and/or DIE tended to have the lowest indicators, whereas women with SE had the highest indicators. Our research highlights that the relationship between women's adiposity and endometriosis severity and typology may be more complicated than prior research indicates.

Male Factor Treatment · Medical Management

Effect of Folic Acid and Zinc Supplementation in Men on Semen Quality and Live Birth Among Couples Undergoing Infertility Treatment: A Randomized Clinical Trial

Schisterman EF et al., 2020 JAMA

Dietary supplements marketed for male fertility commonly contain folic acid and zinc based on limited prior evidence for improving semen quality. However, no large-scale trial has examined the efficacy of this therapy for improving semen quality or live birth. To determine the effect of daily folic acid and zinc supplementation on semen quality and live birth.Design, setting, and participantsThe Folic Acid and Zinc Supplementation Trial was a multicenter randomized clinical trial. Couples (n = 2370; men aged ≥18 years and women aged 18-45 years) planning infertility treatment were enrolled at 4 US reproductive endocrinology and infertility care study centers between June 2013 and December 2017. The last 6-month study visit for semen collection occurred during August 2018, with chart abstraction of live birth and pregnancy information completed during April 2019. Men were block randomized by study center and planned infertility treatment (in vitro fertilization, other treatment at a study site, and other treatment at an outside clinic) to receive either 5 mg of folic acid and 30 mg of elemental zinc (n = 1185) or placebo (n = 1185) daily for 6 months.Main outcomes and measuresThe co-primary outcomes were live birth (resulting from pregnancies occurring within 9 months of randomization) and semen quality parameters (sperm concentration, motility, morphology, volume, DNA fragmentation, and total motile sperm count) at 6 months after randomization. Among 2370 men who were randomized (mean age, 33 years), 1773 (75%) attended the final 6-month study visit. Live birth outcomes were available for all couples, and 1629 men (69%) had semen available for analysis at 6 months after randomization. Live birth was not significantly different between treatment groups (404 [34%] in the folic acid and zinc group and 416 [35%] in the placebo group; risk difference, -0.9% [95% CI, -4.7% to 2.8%]). Most of the semen quality parameters (sperm concentration, motility, morphology, volume, and total motile sperm count) were not significantly different between treatment groups at 6 months after randomization. A statistically significant increase in DNA fragmentation was observed with folic acid and zinc supplementation (mean of 29.7% for percentage of DNA fragmentation in the folic acid and zinc group and 27.2% in the placebo group; mean difference, 2.4% [95% CI, 0.5% to 4.4%]). Gastrointestinal symptoms were more common with folic acid and zinc supplementation compared with placebo (abdominal discomfort or pain: 66 [6%] vs 40 [3%], respectively; nausea: 50 [4%] vs 24 [2%]; and vomiting: 32 [3%] vs 17 [1%]). Conclusions and relevanceAmong a general population of couples seeking infertility treatment, the use of folic acid and zinc supplementation by male partners, compared with placebo, did not significantly improve semen quality or couples' live birth rates. These findings do not support the use of folic acid and zinc supplementation by male partners in the treatment of infertility. ClinicalTrials.gov Identifier: NCT01857310.

Substances · Tobacco and Nicotine

Modifiable life style factors and risk for incident endometriosis

Hemmert R et al., 2018 Paediatr Perinat Epidemiol

Caffeine, alcohol, smoking and physical activity are known to alter sex steroid synthesis, which may affect hormone-dependent gynaecologic disease risk, such as endometriosis; however, few studies have assessed life style factors prior to endometriosis diagnosis. Four hundred and seventy three women, ages 18-44 years, underwent laparoscopy or laparotomy, regardless of clinical indication, at 14 clinic sites, 2007-2009. Women with prior surgically confirmed endometriosis were excluded. Life style factors were assessed prior to surgery. Adjusted risk ratios (RR) of endometriosis by caffeine, alcohol, smoking (serum cotinine), and physical activity were estimated, adjusting for age, marital status, education, race/ethnicity, age at menarche, gravidity, BMI, study site, and other life style factors. There were no associations between women with endometriosis and alcohol consumption (RR 0.9, 95% CI 0.7, 1.3), caffeine consumption (RR 1.1, 95% CI 0.8, 1.5), or smoking (serum cotinine <10 vs ≥10 ng/mL; RR 1.0, 95% CI 0.7, 1.6). Similar null findings were found between endometriosis and weekly occurrences of physical activity and total walking, moderate, and vigorous activity; a modest trend was found between total daily sitting time and increased endometriosis risk. This study, which is unique in its capture of life style exposures prior to incident endometriosis diagnosis, largely found no association between alcohol, caffeine, smoking, and physical activity and risk of endometriosis.

Measurement and Statistics · Statistical Methods

Endometriosis diagnosis and staging by operating surgeon and expert review using multiple diagnostic tools: an inter-rater agreement study

Schliep KC et al., 2017 BJOG Open Access

To determine agreement on endometriosis diagnosis between real-time laparoscopy and subsequent expert review of digital images, operative reports, magnetic resonance imaging (MRI), and histopathology, viewed sequentially. Inter-rater agreement study. Five urban surgical centres. Population: Women, aged 18-44 years, who underwent a laparoscopy regardless of clinical indication. A random sample of 105 women with and 43 women without a postoperative endometriosis diagnosis was obtained from the ENDO study. Laparoscopies were diagnosed, digitally recorded, and reassessed. Inter-observer agreement of endometriosis diagnosis and staging according to the revised American Society for Reproductive Medicine criteria. Prevalence and bias-adjusted kappa values (κ) were calculated for diagnosis, and weighted κ values were calculated for staging. Surgeons and expert reviewers had substantial agreement on diagnosis and staging after viewing digital images (n = 148; mean κ = 0.67, range 0.61-0.69; mean κ = 0.64, range 0.53-0.78, respectively) and after additionally viewing operative reports (n = 148; mean κ = 0.88, range 0.85-0.89; mean κ = 0.85, range 0.84-0.86, respectively). Although additionally viewing MRI findings (n = 36) did not greatly impact agreement, agreement substantially decreased after viewing histological findings (n = 67), with expert reviewers changing their assessment from a positive to a negative diagnosis in up to 20% of cases. Although these findings suggest that misclassification bias in the diagnosis or staging of endometriosis via visualised disease is minimal, they should alert gynaecologists who review operative images in order to make decisions on endometriosis treatment that operative reports/drawings and histopathology, but not necessarily MRI, will improve their ability to make sound judgments. Tweetable Abstract: Endometriosis diagnosis and staging agreement between expert reviewers and operating surgeons was substantial.

Fertility and Outcomes · Conception After Excision

Women's Reproductive History Before the Diagnosis of Incident Endometriosis

Buck Louis GM et al., 2016 J Womens Health (Larchmt) Open Access

Endometriosis is a gynecologic disease reported to be associated with infertility and, possibly, adverse pregnancy outcomes. While considerable research focuses on pregnancy outcomes following diagnosis and/or treatment, few data actually describe women's reproductive history before diagnosis for a more complete understanding of endometriosis and reproduction. The study sample comprised 473 women (aged 18-44 years) undergoing laparoscopies or laparotomies, irrespective of surgical indication at 14 clinical sites, during the period 2007-2009. Upon enrollment and before surgery, women were queried about pregnancy intentions and the time required to become pregnant for planned pregnancies. Endometriosis was defined as surgically visualized disease. Using discrete time survival analysis, we estimated fecundability odds ratios (FORs) and 95% confidence intervals (CIs) to assess time to pregnancy (TTP) after adjusting for potential confounders (age, body composition, cigarette smoking, site). Generalized estimating equations accounted for multiple pregnancy attempts per woman. FORs ResultsApproximately 66% and 69% of women with and without endometriosis, respectively, reported having a planned pregnancy before surgery, respectively. After adjustment, an endometriosis diagnosis was associated with ≈29% reduction in fecundity or a longer TTP across all pregnancy-trying attempts (adjusted FOR = 0.71; 95% CI 0.46-1.10). While FORs were consistently ConclusionsWomen with endometriosis had a longer TTP than unaffected women, irrespective of disease severity, although the findings did not achieve significance. Prior reproductive history may be informative for predicting fecundity and pregnancy outcomes following diagnosis/treatment.

Pelvic Pain · Chronic Pelvic Pain

Sexual and physical abuse and gynecologic disorders

Schliep KC et al., 2016 Hum Reprod Open Access

Is sexual and/or physical abuse history associated with incident endometriosis diagnosis or other gynecologic disorders among premenopausal women undergoing diagnostic and/or therapeutic laparoscopy or laparotomy regardless of clinical indication? No association was observed between either a history of sexual or physical abuse and risk of endometriosis, ovarian cysts or fibroids; however, a history of physical abuse was associated with a higher likelihood of adhesions after taking into account important confounding and mediating factors. Sexual and physical abuse may alter neuroendocrine-immune processes leading to a higher risk for endometriosis and other noninfectious gynecologic disorders, but few studies have assessed abuse history prior to diagnosis. STUDY DESIGN, SIZE, Duration: The study population for these analyses includes the ENDO Study (2007-2009) operative cohort: 473 women, ages 18-44 years, who underwent a diagnostic and/or therapeutic laparoscopy or laparotomy at 1 of the 14 surgical centers located in Salt Lake City, UT, USA or San Francisco, CA, USA. Women with a history of surgically confirmed endometriosis were excluded. PARTICIPANTS/MATERIALS, Setting and Prior to surgery, women completed standardized abuse questionnaires. Relative risk (RR) of incident endometriosis, uterine fibroids, adhesions or ovarian cysts by abuse history were estimated, adjusting for age, race/ethnicity, education, marital status, smoking, gravidity and recruitment site. We assessed whether a history of chronic pelvic pain, depression, or STIs explained any relationships via mediation analyses. Main Results and Role of Chance: 43 and 39% of women reported experiencing sexual and physical abuse. No association was observed between either a history of sexual or physical abuse, versus no history, and risk of endometriosis (aRR: 1.00 [95% confidence interval (CI): 0.80-1.25]); aRR: 0.83 [95% CI: 0.65-1.06]), ovarian cysts (aRR: 0.67 [95% CI: 0.39-1.15]); aRR: 0.60 [95% CI: 0.34-1.09]) or fibroids (aRR: 1.25 [95% CI: 0.85-1.83]); aRR: 1.36 [95% CI: 0.92-2.01]). Conversely, a history of physical abuse, versus no history, was associated with higher risk of adhesions (aRR: 2.39 [95% CI: 1.18-4.85]). We found no indication that the effect of abuse on women's adhesion risk could be explained by a history of chronic pelvic pain, depression or STIs. LIMITATIONS, Limitations to our study include inquiries on childhood physical but not sexual abuse. Additionally, we did not inquire about childhood or adulthood emotional support systems, found to buffer the negative impact of stress on gynecologic health. Abuse may be associated with some but not all gynecologic disorders with neuroendocrine-inflammatory origin. High prevalence of abuse reporting supports the need for care providers to screen for abuse and initiate appropriate follow-up. Supported by the Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development (contracts NO1-DK-6-3428, NO1-DK-6-3427, and 10001406-02). The authors have no potential competing interests.

Pelvic Pain · Chronic Pelvic Pain

Pain typology and incident endometriosis

Mumford SL et al., 2015 Hum Reprod

What are the pain characteristics among women, with no prior endometriosis diagnosis, undergoing laparoscopy or laparotomy regardless of clinical indication? Women with surgically visualized endometriosis reported the highest chronic/cyclic pain and significantly greater dyspareunia, dysmenorrhea, and dyschezia compared with women with other gynecologic pathology (including uterine fibroids, pelvic adhesions, benign ovarian cysts, neoplasms and congenital Müllerian anomalies) or a normal pelvis. Prior research has shown that various treatments for pain associated with endometriosis can be effective, making identification of specific pain characteristics in relation to endometriosis necessary for informing disease diagnosis and management. STUDY DESIGN, SIZE, The study population for these analyses includes the ENDO Study (2007-2009) operative cohort: 473 women, ages 18-44 years, who underwent a diagnostic and/or therapeutic laparoscopy or laparotomy at one of 14 surgical centers located in Salt Lake City, UT or San Francisco, CA. Women with a history of surgically confirmed endometriosis were excluded. PARTICIPANTS/MATERIALS, Endometriosis was defined as surgically visualized disease; staging was based on revised American Society for Reproductive Medicine (rASRM) criteria. All women completed a computer-assisted personal interview at baseline specifying 17 types of pain (rating severity via 11-point visual analog scale) and identifying any of 35 perineal and 60 full-body front and 60 full-body back sites for which they experienced pain in the last 6 months. MAIN There was a high prevalence (≥30%) of chronic and cyclic pelvic pain reported by the entire study cohort regardless of post-operative diagnosis. However, women with a post-operative endometriosis diagnosis, compared with women diagnosed with other gynecologic disorders or a normal pelvis, reported more cyclic pelvic pain (49.5% versus 31.0% and 33.1%, P < 0.001). Additionally, women with endometriosis compared with women with a normal pelvis experienced more chronic pain (44.2 versus 30.2%, P = 0.04). Deep pain with intercourse, cramping with periods, and pain with bowel elimination were much more likely reported in women with versus without endometriosis (all P < 0.002). A higher percentage of women diagnosed with endometriosis compared with women with a normal pelvis reported vaginal (22.6 versus 10.3%, P < 0.01), right labial (18.4 versus 8.1%, P < 0.05) and left labial pain (15.3 versus 3.7%, P < 0.01) along with pain in the right/left hypogastric and umbilical abdominopelvic regions (P < 0.05 for all). Among women with endometriosis, no clear and consistent patterns emerged regarding pain characteristics and endometriosis staging or anatomic location. LIMITATIONS, Interpretation of our findings requires caution given that we were limited in our assessment of pain characteristics by endometriosis staging and anatomic location due to the majority of women having minimal (stage I) disease (56%) and lesions in peritoneum-only location (51%). Significance tests for pain topology related to gynecologic pathology were not corrected for multiple comparisons. Results of our research suggest that while women with endometriosis appear to have higher pelvic pain, particularly dyspareunia, dysmenorrhea, dyschezia and pain in the vaginal and abdominopelvic area than women with other gynecologic disorders or a normal pelvis, pelvic pain is commonly reported among women undergoing laparoscopy, even among women with no identified gynecologic pathology. Future research should explore causes of pelvic pain among women who seek out gynecologic care but with no apparent gynecologic pathology. Given our and other's research showing little correlation between pelvic pain and rASRM staging among women with endometriosis, further development and use of a classification system that can better predict outcomes for endometriosis patients with pelvic pain for both surgical and nonsurgical treatment is needed. Supported by the Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development (contracts NO1-DK-6-3428, NO1-DK-6-3427, and 10001406-02). The authors have no potential competing interests.

Environmental Exposures · Heavy Metals

Trace elements and endometriosis: the ENDO study

Pollack AZ et al., 2013 Reprod Toxicol Open Access

There has been limited study of trace elements and endometriosis. Using a matched cohort design, 473 women aged 18-44 years were recruited into an operative cohort, along with 131 similarly aged women recruited into a population cohort. Endometriosis was defined as surgically visualized disease in the operative cohort, and magnetic resonance imaging diagnosed disease in the population cohort. Twenty trace elements in urine and three in blood were quantified using inductively coupled plasma mass spectrometry. Logistic regression estimated the adjusted odds (aOR) of endometriosis diagnosis for each element by cohort. No association was observed between any element and endometriosis in the population cohort. In the operative cohort, blood cadmium was associated with a reduced odds of diagnosis (aOR=0.55; 95% CI: 0.31, 0.98), while urinary chromium and copper reflected an increased odds (aOR=1.97; 95% CI: 1.21, 3.19; aOR=2.66; 95% CI: 1.26, 5.64, respectively). The varied associations underscore the need for continued research.

Diagnosis · Imaging

Risk factors associated with endometriosis: importance of study population for characterizing disease in the ENDO Study

Peterson CM et al., 2013 Am J Obstet Gynecol Open Access

We sought to identify risk factors for endometriosis and their consistency across study populations in the Endometriosis: Natural History, Diagnosis, and Outcomes (ENDO) Study. In this prospective matched, exposure cohort design, 495 women aged 18-44 years undergoing pelvic surgery (exposed to surgery, operative cohort) were compared to an ageand residence-matched population cohort of 131 women (unexposed to surgery, population cohort). Endometriosis was diagnosed visually at laparoscopy/laparotomy or by pelvic magnetic resonance imaging in the operative and population cohorts, respectively. Logistic regression estimated the adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for each cohort. The incidence of visualized endometriosis was 40% in the operative cohort (11.8% stage 3-4 by revised criteria from the American Society for Reproductive Medicine), and 11% stage 3-4 in the population cohort by magnetic resonance imaging. An infertility history increased the odds of an endometriosis diagnosis in both the operative (AOR, 2.43; 95% CI, 1.57-3.76) and population (AOR, 7.91; 95% CI, 1.69-37.2) cohorts. In the operative cohort only, dysmenorrhea (AOR, 2.46; 95% CI, 1.28-4.72) and pelvic pain (AOR, 3.67; 95% CI, 2.44-5.50) increased the odds of diagnosis, while gravidity (AOR, 0.49; 95% CI, 0.32-0.75), parity (AOR, 0.42; 95% CI, 0.28-0.64), and body mass index (AOR, 0.95; 95% CI, 0.93-0.98) decreased the odds of diagnosis. In all sensitivity analyses for different diagnostic subgroups, infertility history remained a strong risk factor. An infertility history was a consistent risk factor for endometriosis in both the operative and population cohorts of the ENDO Study. Additionally, identified risk factors for endometriosis vary based upon cohort selection and diagnostic accuracy. Finally, endometriosis in the population may be more common than recognized.

Environmental Exposures · Endocrine Disrupting Chemicals

Bisphenol A and phthalates and endometriosis: the Endometriosis: Natural History, Diagnosis and Outcomes Study

Buck Louis GM et al., 2013 Fertil Steril Open Access

To assess in utero exposures and the odds of an endometriosis diagnosis. Matched cohort design. Fourteen participating clinical centers in geographically defined areas in Utah and California. PATIENT(S): Operative cohort comprised 473 women undergoing laparoscopy/laparotomy, and an ageand residence-matched population cohort comprising 127 women undergoing pelvic magnetic resonance imaging (MRI), 2007-2009. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Women completed standardized interviews before surgery or MRI regarding in utero exposures: mothers' lifestyle during the index pregnancy, and the index woman's gestation and birth size. Endometriosis was defined as visually confirmed disease in the operative cohort, and MRI visualized disease in the population cohort. The odds of an endometriosis diagnosis and corresponding 95% confidence intervals (CI) were estimated for each exposure by cohort using logistic regression and adjusting for current smoking, age at menarche, body mass index, and study site. RESULT(S): Endometriosis was diagnosed in 41% and 11% of women in the operative and population cohorts, respectively. In the primary analysis, adjust odds ratios (AORs) were elevated for maternal vitamin usage (1.27; 95% CI, 0.85-1.91), maternal cigarette smoking (1.16; 95% CI = 0.61-2.24), and low birth weight (1.1; 95% CI, 0.92-1.32). Reduced odds were observed for maternal usage of caffeine (0.99; 95% CI, 0.64-1.54), alcohol (0.82; 95% CI, 0.35-1.94), paternal cigarette smoking (0.72; 95% CI, 0.43-1.19), and preterm delivery (0.98; 95% CI, 0.47-2.03). Sensitivity analyses mostly upheld the primary results except for a decreased AOR for preterm birth (0.41; 95% CI, 0.18-0.94) when restricting to visualized and histologically confirmed endometriosis in the operative cohort. CONCLUSION(S): In utero exposures were not statistically significantly associated with the odds of an endometriosis diagnosis in either cohort.

Environmental Exposures · Persistent Organic Pollutants

Perfluorochemicals and endometriosis: the ENDO study

Louis GMB et al., 2012 Epidemiology Open Access

Environmental chemicals may be associated with endometriosis. No published research has focused on the possible role of perfluorochemicals (PFCs) despite their widespread presence in human tissues. We formulated two samples. The first was an operative sample comprising 495 women aged 18-44 years scheduled for laparoscopy/laparotomy at one of 14 participating clinical sites in the Salt Lake City or San Francisco area, 2007-2009. The second was a population-based sample comprising 131 women matched to the operative sample on age and residence within a 50-mile radius of participating clinics. Interviews and anthropometric assessments were conducted at enrollment, along with blood collection for the analysis of nine PFCs, which were quantified using liquid chromatography-tandem mass spectrometry. Endometriosis was defined based on surgical visualization (in the operative sample) or magnetic resonance imaging (in the population sample). Using logistic regression, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) for each PFC (log-transformed), adjusting for age and body mass index, and then parity. Serum perfluorooctanoic acid (PFOA; OR = 1.89 [95% CI = 1.17-3.06]) and perfluorononanoic acid (2.20 [1.02-4.75]) were associated with endometriosis in the operative sample; findings were moderately attenuated with parity adjustment (1.62 [0.99-2.66] and 1.99 [0.91-4.33], respectively). Perfluorooctane sulfonic acid (1.86 [1.05-3.30]) and PFOA (2.58 [1.18-5.64]) increased the odds for moderate/severe endometriosis, although the odds were similarly attenuated with parity adjustment (OR = 1.50 and 1.86, respectively). Select PFCs were associated with an endometriosis diagnosis. These associations await corroboration.

Measurement and Statistics · Research Tooling and Reproducibility

Interrater and intrarater reliability in the diagnosis and staging of endometriosis

Schliep KC et al., 2012 Obstet Gynecol Open Access

To estimate the interrater and intrarater reliability of endometriosis diagnosis and severity of disease among gynecologic surgeons viewing operative digital images. The study population comprised a random sample (n=148 [36%]) of women who participated in the Endometriosis: Natural History, Diagnosis and Outcomes study. Four academic expert and four local, specialized expert surgeons reviewed the images, diagnosed the presence or absence of endometriosis for each woman, and rated severity using the revised American Society for Reproductive Medicine (ASRM) criteria. Interrater-level and intrarater-level agreement were calculated for both endometriosis diagnosis and staging. The interrater reliability for endometriosis diagnosis among the eight surgeons was substantial: Fleiss κ=0.69 (95% confidence interval [CI] 0.64-0.74). Surgeons agreed on revised ASRM endometriosis staging criteria after experienced assessment in a majority of cases (mean 61%, range 52-75%) with moderate interrater reliability: Fleiss κ=0.44 (95% CI 0.41-0.47). The intrarater reliability for experienced assessment compared with computer-assisted revised ASRM staging was almost perfect (mean weighted κ=0.95, range 0.89-0.99). Substantial reliability was found for revised ASRM endometriosis diagnosis, whereas moderate reliability was observed for staging. Almost perfect reliability was observed for surgeons' rating of disease severity compared with computerized-assisted, checklist-based staging. Findings suggest that reliability in endometriosis diagnosis is not greatly altered by location or composition of surgeons, supporting the conduct of multisite studies or compilation of endometriosis data across clinical centers. Although surgeons appear to be skilled at assessing endometriosis stage intuitively, how staging of disease burden correlates with clinical outcomes remains to be developed.

Environmental Exposures · Persistent Organic Pollutants

Persistent lipophilic environmental chemicals and endometriosis: the ENDO Study

Buck Louis GM et al., 2012 Environ Health Perspect Open Access

An equivocal literature exists regarding the relation between persistent organochlorine pollutants (POPs) and endometriosis in women, with differences attributed to methodologies. We assessed the association between POPs and the odds of an endometriosis diagnosis and the consistency of findings by biological medium and study cohort. Using a matched cohort design, we assembled an operative cohort of women 18-44 years of age undergoing laparoscopy or laparotomy at 14 participating clinical centers from 2007 to 2009 and a population-based cohort matched on age and residence within a 50-mile catchment area of the clinical centers. Endometriosis was defined as visualized disease in the operative cohort and as diagnosed by magnetic resonance imaging in the population cohort. Logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for each POP in relation to an endometriosis diagnosis, with separate models run for each medium (omental fat in the operative cohort, serum in both cohorts) and cohort. Adjusted models included age, body mass index, breast-feeding conditional on parity, cotinine, and lipids. Concentrations were higher in omental fat than in serum for all POPs. In the operative cohort, γ-hexachlorocyclohexane (γ-HCH) was the only POP with a significant positive association with endometriosis [per 1-SD increase in log-transformed γ-HCH: adjusted OR (AOR) = 1.27; 95% CI: 1.01, 1.59]; β-HCH was the only significant predictor in the population cohort (per 1-SD increase in log-transformed β-HCH: AOR = 1.72; 95% CI: 1.09, 2.72). Using a matched cohort design, we found that cohort-specific and biological-medium-specific POPs were associated with endometriosis, underscoring the importance of methodological considerations when interpreting findings.

Diagnosis · Imaging

Incidence of endometriosis by study population and diagnostic method: the ENDO study

Buck Louis GM et al., 2011 Fertil Steril Open Access

To estimate the incidence of endometriosis in an operative cohort of women seeking clinical care and in a matched population cohort to delineate more fully the scope and magnitude of endometriosis in the context of and beyond clinical care. Matched-exposure cohort design. Surgical centers in the Salt Lake City, Utah, and San Francisco, California, areas. PATIENT(S): The operative cohort comprised 495 women undergoing laparoscopy/laparotomy between 2007 and 2009, and the population cohort comprised 131 women from the surgical centers' catchment areas. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Incidence of endometriosis by diagnostic method in the operative cohort and by pelvic magnetic resonance imaged (MRI) disease in the population cohort. RESULT(S): Endometriosis incidence in the operative cohort ranged by two orders of magnitude by diagnostic 0.7% for only histology, 7% for only MRI, and 41% for visualized disease. Endometriosis staging was skewed toward minimal (58%) and mild disease (15%). The incidence of MRI-diagnosed endometriosis was 11% in the population cohort. CONCLUSION(S): Endometriosis incidence is dependent on the diagnostic method and choice of sampling framework. Conservatively, 11% of women have undiagnosed endometriosis at the population level, with implications for the design and interpretation of etiologic research.