Diagnosis of Stage I Endometriosis: Comparing Visual Inspection to Histologic Biopsy Specimen

Insights from Mendelian randomization and genetic correlation analyses into the relationship between endometriosis and its comorbidities

BACKGROUND

Endometriosis remains a poorly understood disease, despite its high prevalence and debilitating symptoms. The overlap in symptoms and the increased risk of multiple other traits in women with endometriosis is becoming increasingly apparent through epidemiological data. Genetic studies offer a method of investigating these comorbid relationships through the assessment of causal relationships with Mendelian randomization (MR), as well as identification of shared genetic variants and genes involved across traits. This has the capacity to identify risk factors for endometriosis as well as provide insight into the aetiology of disease.

OBJECTIVE AND RATIONALE

We aim to review the current literature assessing the relationship between endometriosis and other traits using genomic data, primarily through the methods of MR and genetic correlation. We critically examine the limitations of these studies in accordance with the assumptions of the utilized methods.

SEARCH METHODS

The PubMed database was used to search for peer-reviewed original research articles using the terms 'Mendelian randomization endometriosis' and '"genetic correlation" endometriosis'. Additionally, a Google Scholar search using the terms '"endometriosis" "mendelian randomization" "genetic correlation"' was performed. All relevant publications (n = 21) published up until 7 October 2022 were included in this review. Upon compilation of all traits with published MR and/or genetic correlation with endometriosis, additional epidemiological and genetic information on their comorbidity with endometriosis was sourced by searching for the trait in conjunction with 'endometriosis' on Google Scholar.

OUTCOMES

The association between endometriosis and multiple pain, gynaecological, cancer, inflammatory, gastrointestinal, psychological, and anthropometric traits has been assessed using MR analysis and genetic correlation analysis. Genetic correlation analyses provide evidence that genetic factors contributing to endometriosis are shared with multiple traits: migraine, uterine fibroids, subtypes of ovarian cancer, melanoma, asthma, gastro-oesophageal reflux disease, gastritis/duodenitis, and depression, suggesting the involvement of multiple biological mechanisms in endometriosis. The assessment of causality with MR has revealed several potential causes (e.g. depression) and outcomes (e.g. ovarian cancer and uterine fibroids) of a genetic predisposition to endometriosis; however, interpretation of these results requires consideration of potential violations of the MR assumptions.

WIDER IMPLICATIONS

Genomic studies have demonstrated that there is a molecular basis for the co-occurrence of endometriosis with other traits. Dissection of this overlap has identified shared genes and pathways, which provide insight into the biology of endometriosis. Thoughtful MR studies are necessary to ascertain causality of the comorbidities of endometriosis. Given the significant diagnostic delay of endometriosis of 7-11 years, determining risk factors is necessary to aid diagnosis and reduce the disease burden. Identification of traits for which endometriosis is a risk factor is important for holistic treatment and counselling of the patient. The use of genomic data to disentangle the overlap of endometriosis with other traits has provided insights into the aetiology of endometriosis.

Genomic characterisation of the overlap of endometriosis with 76 comorbidities identifies pleiotropic and causal mechanisms underlying disease risk

Comorbid conditions can be driven by underlying pleiotropic and causal mechanisms that can provide insights into shared molecular and biological processes contributing to disease risk. Endometriosis is a chronic condition affecting one in nine women of reproductive age and poses many challenges including lengthy diagnostic delays and limited treatment efficacy owing to poor understanding of disease aetiology. To shed light on the underlying biological mechanisms and to identify potential risk factors, we examine the epidemiological and genomic relationship between endometriosis and its comorbidities. In the UK Biobank 292 ICD10 codes were epidemiologically correlated with endometriosis diagnosis, including gynaecological, immune, infection, pain, psychiatric, cancer, gastrointestinal, urinary, bone and cardiovascular traits. A subset of the identified comorbidities (n = 76) underwent follow-up genetic analysis. Whilst Mendelian randomisation suggested causality was not responsible for most comorbid relationships, 22 traits were genetically correlated with endometriosis, including pain, gynaecological and gastrointestinal traits, suggestive of a shared genetic background. Pleiotropic genetic variants and genes were identified using gene-based and colocalisation analysis. Shared genetic risk factors and potential target genes suggest a diverse collection of biological systems are involved in these comorbid relationships including coagulation factors, development of the female reproductive tract and cell proliferation. These findings highlight the diversity of traits with epidemiological and genomic overlap with endometriosis and implicate a key role for pleiotropy in the comorbid relationships.

Antibody Arrays Identified Cycle-Dependent Plasma Biomarker Candidates of Peritoneal Endometriosis

Endometriosis is an estrogen-dependent inflammatory disease affecting women in their reproductive age. Due to non-specific symptoms, women with endometriosis are often misdiagnosed or are accurately diagnosed only after several years. Diagnosis of peritoneal endometriosis is especially challenging and relies only on laparoscopic surgery. To date, different molecules have been proposed as potential non-invasive biomarkers of endometriosis; however, none have been confirmed as clinically useful. Therefore, this study aimed to discover novel plasma biomarker candidates for peritoneal endometriosis using an antibody array platform. This study included patients with endometriosis-like symptoms characterized by the absence (controls) or presence of peritoneal endometriosis (cases) after laparoscopic surgery and histological evaluation. Patients were further divided into secretory and proliferative groups, according to the phase of their menstrual cycle. Their plasma samples were collected and analyzed on an antibody array platform targeting more than 1350 proteins with over 1820 antibodies. In the proliferative group, the analysis revealed three differential proteins between cases and controls: ITB3, ITA2B2, and ACVL-1. In the secretory group, none of the examined proteins reached the log-fold change (logFC) and significance thresholds simultaneously. The potential of the identified differential proteins as plasma biomarker candidates for peritoneal endometriosis should be evaluated on a larger cohort, and their role in endometriosis should be investigated in further studies.

Diagnosis of Endometriosis at Laparoscopy: A Validation Study Comparing Surgeon Visualization with Histologic Findings

OBJECTIVE

This study aimed to evaluate the validity of laparoscopic visualization for the diagnosis of endometriosis compared with histopathology.

METHODS

We conducted a retrospective chart review at a tertiary care hospital in Canada for the period of April 1, 2016 to March 31, 2017. Of 1069 women, 96 were selected for having undergone laparoscopic visualization and concurrent histopathological biopsy for suspected endometriosis. Standard measures of validity for diagnostic tests (sensitivity, specificity, positive predictive and negative predictive values, accuracy) were used.

RESULTS

Mean age of the 96 women included was 40 ± 7.2 years, and median gravidity and parity were 1 (IQR 0-3) and 0 (IQR 0-2), respectively. Common symptoms were abdominal and pelvic pain (41.7%), menstrual bleeding concerns (34.4%), dysmenorrhea (29.2%), and infertility (8.3%). Approximately one-third of women had endometriomas (31.3%), while more than half had deep infiltrating endometriosis (59.4%). The diagnosis of endometriosis was made by surgeons at laparoscopic visualization in 82.3% of women and by histopathology in 74.0%. Using histopathology as the gold standard, sensitivity for laparoscopic visualization was 90.1% (95% CI 81.0-95.1), while specificity was 40.0% (95% CI 23.4-59.3). Positive and negative predictive values were 81.0% (95% CI 71.0-88.1) and 58.8% (95% CI 36.0-78.4), respectively; and the accuracy was 77.1% (95% CI 67.7-84.4).

CONCLUSION

Although laparoscopic visualization had relatively high sensitivity and positive predictive value, its specificity and negative predictive value were relatively low. These findings support the use of laparoscopic visualization with histopathological analysis for accurate diagnosis of endometriosis.

Endometriosis is a chronic systemic disease: clinical challenges and novel innovations

Endometriosis is a common disease affecting 5-10% of women of reproductive age globally. However, despite its prevalence, diagnosis is typically delayed by years, misdiagnosis is common, and delivery of effective therapy is prolonged. Identification and prompt treatment of endometriosis are essential and facilitated by accurate clinical diagnosis. Endometriosis is classically defined as a chronic, gynaecological disease characterised by endometrial-like tissue present outside of the uterus and is thought to arise by retrograde menstruation. However, this description is outdated and no longer reflects the true scope and manifestations of the disease. The clinical presentation is varied, the presence of pelvic lesions is heterogeneous, and the manifestations of the disease outside of the female reproductive tract remain poorly understood. Endometriosis is now considered a systemic disease rather than a disease predominantly affecting the pelvis. Endometriosis affects metabolism in liver and adipose tissue, leads to systemic inflammation, and alters gene expression in the brain that causes pain sensitisation and mood disorders. The full effect of the disease is not fully recognised and goes far beyond the pelvis. Recognition of the full scope of the disease will facilitate clinical diagnosis and allow for more comprehensive treatment than currently available. Progestins and low-dose oral contraceptives are unsuccessful in a third of symptomatic women globally, probably as a result of progesterone resistance. Oral gonadotropin-releasing hormone (GnRH) antagonists constitute an effective and tolerable therapeutic alternative when first-line medications do not work. The development of GnRH antagonists has resulted in oral drugs that have fewer side-effects than other therapies and has allowed for rapid movement between treatments to optimise and personalise endometriosis care. In this Review, we discuss the latest understanding of endometriosis as a systemic disease with multiple manifestations outside the parameters of classic gynaecological disease.

Can Narrowband Imaging Improve the Laparoscopic Identification of Superficial Endometriosis? A Prospective Cohort Trial

STUDY OBJECTIVE

To assess the usefulness of narrowband imaging (NBI) to detect additional areas of endometriosis not identified by standard white light in patients undergoing laparoscopy for the investigation of pelvic pain.

DESIGN

A prospective cohort trial (Canadian Task Force classification II). Evidence obtained from a well-designed cohort study.

SETTING

A tertiary laparoscopic subspecialty unit in Melbourne, Australia.

PATIENTS

Fifty-seven patients undergoing laparoscopy for the investigation of pelvic pain were recruited. Fifty-three patients were eligible for analysis.

INTERVENTIONS

Patients underwent standard white-light laparoscopy of the pelvis followed by NBI survey to assess for any additional areas suspicious for endometriosis.

MEASUREMENTS AND MAIN RESULTS

All identified areas of possible endometriosis were resected and sent for blinded histopathological analysis. The additional predictive value of NBI was 0% if the preceding white-light survey was negative and 86% if the preceding white-light survey was positive.

CONCLUSION

The use of NBI at laparoscopy for the investigation of pelvic pain is beneficial in finding additional areas of endometriosis if endometriosis is already suspected after white-light survey in a tertiary laparoscopic unit. Further research in nonspecialized units may show additional benefit and requires further research. NBI may also be useful as a diagnostic aid for trainees.

Techniques in minimally invasive surgery for advanced endometriosis

PURPOSE OF REVIEW

Surgery can be an important treatment option for women with symptomatic endometriosis. This review summarizes the recommended preoperative work up and techniques in minimally invasive surgery for treatment of deeply infiltrating endometriosis (DIE) involving the obliterated posterior cul-de-sac, bowel, urinary tract, and extrapelvic locations.

RECENT FINDINGS

Surgical management of DIE can pose a challenge to the gynecologic surgeon given that an extensive dissection is usually necessary. Given the high risk of recurrence, it is vital that an adequate excision is performed. With improved imaging modalities, preoperative counseling and surgical planning can be optimized. It is essential to execute meticulous surgical technique and include a multidisciplinary surgical team when indicated for optimal results.

SUMMARY

Advanced laparoscopic skills are often necessary to completely excise DIE. A thorough preoperative work up is essential to provide correct patient counseling and incorporation of the preferred surgical team to decrease complications and optimize surgical outcomes. Surgical management of endometriosis is aimed at ameliorating symptoms and preventing recurrence.

Visualization of endometriosis: comparative study of 3-dimensional robotic and 2-dimensional laparoscopic endoscopes

The main objective of this study was to compare results of using the robotic 3D/HD scope and the 2D/HD laparoscope for visual detection of histologically confirmed endometriosis. Three surgeons from different practices enrolled premenopausal women ≥18 years who had elected to undergo robotic-assisted endometriosis resection. Patients were randomized to receive 2D/HD laparoscopic visualization either before or after 3D/HD robotic visualization. Resections then proceeded robotically. The number of histologically confirmed lesions overall and by abdomino-pelvic location, appearance and size was compared by scope type used. During the study, 598 lesions were visualized in 98 patients. Average number of lesions per patient using either scope was 6.1. Mean age was 31 years and 77% were disease stage I/II. On histopathology, 58.4% of lesions resected were consistent with endometriosis. All (100%) of these lesions were detected using the robotic 3D/HD scope and 77.9% using the 2D/HD laparoscope (p < 0.001). Compared to laparoscopic, robotic visualization resulted in detection of more confirmed lesions in all anatomic locations and for most appearances, including the cul-de-sac (100 vs. 79%), atypical appearance (100 vs. 71.3%) and width <5 mm (100 vs. 62%), p's < 0.001). Logistic regression indicated that use of the 3D/HD robotic scope was independently associated with 2.36 times the likelihood (95% CI 1.20, 4.66; p = 0.014) of detecting a confirmed lesion, compared to the 2D/HD laparoscope. Large-scale, long-term studies are needed to substantiate these findings in multiple practice settings and to determine whether 3D robotic versus 2D laparoscopic resection has a beneficial impact on symptomatology, recurrence and fertility outcomes.

Morphologic Features Suggestive of Endometriosis in Nondiagnostic Peritoneal Biopsies

Endometriosis is a common disorder that causes significant morbidity from dysmenorrhea, pelvic pain, and subfertility. Establishment of a definitive diagnosis has important therapeutic implications; however, only approximately 50% of biopsies of laparoscopically suspicious areas provide a diagnosis of endometriosis. Histologic criteria for diagnosis require the presence of endometrial glands or endometrial-type stroma. We hypothesize that other frequently present, but nondiagnostic, histologic features of endometriosis suggest its presence in patients with nondiagnostic peritoneal biopsies. We performed a retrospective clinicopathologic study of morphologic and immunohistochemical features that may improve the histologic diagnosis of endometriosis on laparoscopic peritoneal biopsies. We compared diagnostic (n=88) and nondiagnostic (n=54) peritoneal biopsies from pathologically confirmed endometriosis cases with negative peritoneal biopsies (n=84) from early-stage gynecologic cancer cases. Statistical analysis utilized the Fisher exact test. Multiple morphologic features were significantly increased in nondiagnostic biopsies from patients with endometriosis in comparison with those from negative controls, including foamy macrophages (P=0.0001) and submesothelial stromal clusters (SSCs) (P=0.0008). SSCs ranged from subtle aggregates of spindle cells to nodules of whorled spindle cells with small vessels and extravasated red blood cells resembling stromal endometriosis. Immunohistochemical studies confirmed that ER and CD10-positive SSCs were present in a greater proportion of both nondiagnostic and diagnostic peritoneal biopsies and at a greater number of lesions per biopsy. The overall histologic detection rate of peritoneal biopsies for endometriosis was 62.0%, and inclusion of SSCs with or without foamy macrophages in the diagnostic criteria appreciably increased this rate to between 72.5% and 76.8%. We describe SSCs, which appear to be an early or less developed form of stromal endometriosis, and, when included in the diagnostic criteria, improve the histologic detection rate of endometriosis in peritoneal biopsies.

Sensitivity of Narrow Band Imaging Compared With White Light Imaging for the Detection of Endometriosis

STUDY OBJECTIVE

To evaluate the ability of narrow band imaging (NBI) in conjunction with standard white light imaging to improve the detection and diagnosis of endometriosis during laparoscopic evaluation compared with white light imaging alone. Sensitivity of NBI in detecting endometriosis was assessed and compared with white light imaging.

DESIGN

Randomized controlled trial.

CLASSIFICATION OF STUDY DESIGN

LEVEL I: Evidence obtained from a properly designed, randomized, controlled trial.

SETTING

The trial was conducted in 2 medical centers.

PATIENTS

One hundred sixty-seven women undergoing laparoscopic evaluation for suspected endometriosis and/or infertility were recruited. Of these, 150 were assessable to determine sensitivity of NBI compared with white light imaging for the detection of endometriotic lesions.

INTERVENTIONS

Patients were randomized in a 3:1 ratio to receive white light imaging followed by NBI or white light imaging only. The pelvis was systematically visualized with each assigned imaging modality; lesions were recorded under each visualization and then resected. All patients had white light imaging on the first visualization followed by either a second white light examination (control arm) or NBI examination (intervention arm).

MEASUREMENTS

Pathology of resected lesions was the criterion standard for evaluating sensitivity and was conducted at each institution. The method of detection of the lesion (white light or NBI) was masked. Central pathology review was conducted for a randomly selected 10% sample of specimens and for those lesions visualized under only 1 imaging modality among patients assigned to the intervention arm. The sensitivity was assessed for each modality (white light and NBI) and compared using a McNemar's test.

MAIN RESULTS

Among the group randomized to receive both white light and NBI, 4 patients had lesions detected with NBI but no lesions detected with white light. Among the 255 lesions confirmed as endometriosis by pathologic review, all were detected by NBI for a sensitivity of 100%; 79% were detected by white light imaging (p < .001).

CONCLUSION

The addition of NBI to white light imaging increased the number of endometriotic lesions identified during laparoscopy and the diagnosis of endometriosis compared with the use of white light imaging alone.