Ultrasound-Based Endometriosis Staging System: Validation Study to Predict Complexity of Laparoscopic Surgery

Noninvasive diagnostic imaging for endometriosis part 1: a systematic review of recent developments in ultrasound, combination imaging, and artificial intelligence

Endometriosis affects 1 in 9 women and those assigned female at birth. However, it takes 6.4 years to diagnose using the conventional standard of laparoscopy. Noninvasive imaging enables a timelier diagnosis, reducing diagnostic delay as well as the risk and expense of surgery. This review updates the exponentially increasing literature exploring the diagnostic value of endometriosis specialist transvaginal ultrasound (eTVUS), combinations of eTVUS and specialist magnetic resonance imaging, and artificial intelligence. Concentrating on literature that emerged after the publication of the IDEA consensus in 2016, we identified 6192 publications and reviewed 49 studies focused on diagnosing endometriosis using emerging imaging techniques. The diagnostic performance of eTVUS continues to improve but there are still limitations. eTVUS reliably detects ovarian endometriomas, shows high specificity for deep endometriosis and should be considered diagnostic. However, a negative scan cannot preclude endometriosis as eTVUS shows moderate sensitivity scores for deep endometriosis, with the sonographic evaluation of superficial endometriosis still in its infancy. The fast-growing area of artificial intelligence in endometriosis detection is still evolving, but shows great promise, particularly in the area of combined multimodal techniques. We finalize our commentary by exploring the implications of practice change for surgeons, sonographers, radiologists, and fertility specialists. Direct benefits for endometriosis patients include reduced diagnostic delay, better access to targeted therapeutics, higher quality operative procedures, and improved fertility treatment plans.

CAR Practice Statement on Advanced Pelvic Ultrasound for Endometriosis

The Canadian Association of Radiologists (CAR) Endometriosis Working Group was tasked with providing guidance and benchmarks to ensure the quality of technique and interpretation for advanced imaging modalities associated with diagnosing endometriosis. This practice statement provides an overview of the state of the art of advanced pelvic ultrasound in the diagnosis and mapping of pelvic endometriosis. While acknowledging that advanced pelvic ultrasound in some practices falls within the scope of clinical colleagues rather than imaging departments, the statement seeks to guide radiologists interested in implementing these techniques into their practice for patients referred for evaluation and diagnosis of endometriosis. The statement covers indications, some components of the ultrasound assessment and technique, reporting, and recommendations for starting an ultrasound endometriosis evaluation program.

Anatomical distribution of endometriosis: A cross-sectional analysis of transvaginal ultrasound in symptomatic patients

Purpose

The anatomical distribution of deep endometriosis (DE) is essential in treating patients with symptoms associated with the disease. There is an evidence gap in correlating clinical features and symptoms with disease patterns. The study aimed at determining DE anatomic distribution based on advanced transvaginal ultrasound and describe the relationship with symptoms obtained with the World Endometriosis Foundation Questionnaire.

Methods

A cross-sectional study included 549 ultrasound results and 370 questionnaire responses between July 2018 and January 2021. Descriptive statistics are presented. Continuous variables were compared by a simple t-test and ANOVA and categorical variables by the chi-squared test. Logistic regression and R2 values summarised the relationship between positive ultrasound and possible predictor variables (software SAS version 9.4).

Results

The anatomical locations with signs of endometriosis on ultrasound were the right uterosacral ligament (USL) 23.3% (n = 128), left USL 21.3% (n = 117) and bowel 19.1% (n = 105). Endometriomas in the right and left ovaries (14%, n = 77, and 14.7%, n = 81 respectively), superficial endometriosis in 15.5% (n = 85), torus uterinus in 11.7% (n = 64), Pouch of Douglas (POD) in 9.7% (n = 53), rectovaginal septum in 4.2% (n = 23), vaginal fornix in 3.5% (n = 19). A negative 'sliding-sign' was noted in 25.3% (n = 139), and ovarian medial immobility was noted frequently (left 20.2%, n = 111 and right 16.9%, n = 93). Dyspareunia, dysmenorrhoea, infertility and family history were associated with endometriosis lesions (P < 0.05). Prediction models based on symptomatology presented low discriminatory power.

Discussion

This large real-life cohort associating the description of the anatomical distribution of endometriosis as seen on advanced TVS in symptomatic patients confirmed that uterosacral ligaments, torus uterinus, ovaries and bowel represent the most common anatomical sites of endometriosis. Also, the dynamic abnormalities elicited via ultrasound, such as the uterus 'sliding-sign' and ovarian mobility, remain common. The knowledge of the general locations of identifiable endometriosis on ultrasound and the dynamic abnormalities is essential to sonologists and sonographers in implementing advanced TVS protocols to detect endometriosis. In addition, the different presentations of dyspareunia can be associated with USL and bowel endometriosis. Subfertility might also be associated with USL, ovarian and bowel endometriosis. Nevertheless, prediction models showed suboptimal results.

Conclusions

Endometriosis is mainly distributed in USLs, bowel and ovaries. POD obliteration is frequent. Symptoms can be associated with anatomic locations; however, prediction models showed low clinical applicability.

Endometriosis: A multimodal imaging review

Endometriosis is a chronic inflammatory disorder characterized endometrial-like tissue present outside of the uterus, affecting approximately 10% of reproductive age women. It is associated with abdomino-pelvic pain, infertility and other non - gynecologic symptoms, making it a challenging diagnosis. Several guidelines have been developed by different international societies to diagnose and classify endometriosis, yet areas of controversy and uncertainty remains. Transvaginal ultrasound (TV-US) is the first-line imaging modality used to identify endometriosis due to its accessibility and cost-efficacy. Enhanced sonographic techniques are emerging as a dedicated technique to evaluate deep infiltrating endometriosis (DIE), depending on the expertise of the sonographer as well as the location of the lesions. MRI is an ideal complementary modality to ultrasonography for pre-operative planning as it allows for a larger field-of-view when required and it has high levels of reproducibility and tolerability. Typically, endometriotic lesions appear hypoechoic on ultrasonography. On MRI, classical features include DIE T2 hypointensity, endometrioma T2 hypointensity and T1 hyperintensity, while superficial peritoneal endometriosis (SPE) is described as a small focus of T1 hyperintensity. Imaging has become a critical tool in the diagnosis, surveillance and surgical planning of endometriosis. This literature review is based mostly on studies from the last two decades and aims to provide a detailed overview of the imaging features of endometriosis as well as the advances and usefulness of different imaging modalities for this condition.

Advances in Imaging for Assessing Pelvic Endometriosis

In recent years, due to the development of standardized diagnostic protocols associated with an improvement in the associated technology, the diagnosis of pelvic endometriosis using imaging is becoming a reality. In particular, transvaginal ultrasound and magnetic resonance are today the two imaging techniques that can accurately identify the majority of the phenotypes of endometriosis. This review focuses not only on these most common imaging modalities but also on some additional radiological techniques that were proposed for rectosigmoid colon endometriosis, such as double-contrast barium enema, rectal endoscopic ultrasonography, multidetector computed tomography enema, computed tomography colonography and positron emission tomography-computed tomography with 16α-[18F]fluoro-17β-estradiol.

'Seeing is believing': arguing for diagnostic laparoscopy as a diagnostic test for endometriosis

Endometriosis is a benign disease that can cause pain and infertility in women. Debate exists over how endometriosis should best be diagnosed. On one hand, endometriosis can be diagnosed by directly examining pelvic anatomy via a surgical procedure known as diagnostic laparoscopy. On the other hand, the disease can be diagnosed via non-surgical means such as using medical imaging, the symptoms described by the patient and whether the patient responds to non-surgical therapies such as medication. In this debate article, we argue in favour of diagnostic laparoscopy. We review the safety of the procedure, compare the ability of diagnostic laparoscopy vs medical imaging to detect endometriosis and consider the benefits of formally diagnosing or ruling out the condition.

Adenomyosis is an independent risk factor for complications in deep endometriosis laparoscopic surgery

Deep endometriosis (DE) occurs in 15-30% of patients with endometriosis and is associated with concomitant adenomyosis in around 25-49% of cases. There are no data about the effect of the presence of adenomyosis in terms of surgical outcomes and complications. Thus, the aim of the present study was to evaluate the impact of adenomyosis on surgical complications in women with deep endometriosis undergoing laparoscopic surgery. A retrospective cohort study including women referred to the endometriosis unit of a referral teaching hospital. Two expert sonographers preoperatively diagnosed DE and adenomyosis. DE was defined according to the criteria of the International Deep Endometriosis Analysis group. Adenomyosis was considered when 3 or more ultrasound criteria of the Morphological Uterus Sonographic Assessment group were present. Demographical variables, current medical treatment, symptoms, DE location, surgical time, hospital stay and difference in pre and post hemoglobin levels were collected. The Clavien-Dindo classification was used to assess surgical complications, and multivariate analysis was performed to compare patients with and without adenomyosis. 157 DE patients were included into the study; 77 (49.05%) had adenomyosis according to transvaginal ultrasound (TVS) and were classified in the A group, and 80 (50.95%) had no adenomyosis and were classified in the noA group. Adenomyosis was associated with a higher rate of surgical complications: 33.76% (A group) vs. 12.50% (noA group) (p < 0.001). Multivariate analysis showed a 4.56-fold increased risk of presenting complications in women with adenomyosis (CI 1.90-11.30; p = 0.001) independently of undergoing hysterectomy. There was a statistically significant association between the number of criteria of adenomyosis present in each patient and the proportion of patients presenting surgical complications (p < 0.001). Adenomyosis is an independent preoperative risk factor for surgical complications in DE surgery after adjustment for known demographic, clinical and surgical risk factors.

What to choose and why to use - a critical review on the clinical relevance of rASRM, EFI and Enzian classifications of endometriosis

Background

Endometriosis is a common benign gynaecological disease that affects pelvic structures and causes adhesions. Endometriosis outside the pelvis exists but is rarer. Deep endometriosis may affect organs such as the urinary bladder, ureters, bowel and sacral roots. Adenomyosis (growth of endometrium in the myometrium, sometimes explained by disruption of the uterine junctional zone) frequently co-exists with deep endometriosis. Over the past decades, multiple attempts have been made to describe the anatomical extent of endometriosis. Out of approximately 20 classification systems suggested and published so far, three have gained widespread acceptance. These are the rASRM (American Society of Reproductive Medicine) classification, the Endometriosis Fertility Index (EFI) and the Enzian classification. Ideally, a classification system should be useful both for describing disease extent based on surgical findings and results of imaging methods (ultrasound, magnetic resonance imaging).

Objectives

To highlight the advantages and disadvantages of the three classification systems.

Methods

This is a narrative review based on selected publications and experience of the authors. We discuss the current literature on the use of the rASRM, EFI and Enzian classification systems for describing disease extent with imaging methods and for prediction of fertility, surgical complexity, and risk of surgical complications. We underline the need for one universally acceptable terminology to describe the extent of endometriosis.

Conclusions

A useful classification system for endometriosis should describe the sites and extent of the disease, be related to surgical complexity and to disease-associated symptoms, including subfertility and should satisfy needs of both, imaging specialists for pre-operative classification and surgeons. The need for such a system is obvious and is provided by the #Enzian classification. Future research is necessary to test its validity.

Endometriosis Classification, Staging and Reporting Systems: A Review on the Road to a Universally Accepted Endometriosis Classification

OBJECTIVE

In the field of endometriosis, several classification, staging and reporting systems have been developed. Which endometriosis classification, staging and reporting systems have been published and validated for use in clinical practice?

DATA SOURCES

A systematic PUBMED literature search was performed. Data were extracted and summarized.

METHODS OF STUDY SELECTION

na TABULATION, INTEGRATION AND RESULTS: Twenty-two endometriosis classification, staging and reporting systems have been published between 1973 and 2021, each developed for specific, and different, purposes. There still is no international agreement on how to describe the disease. Studies evaluating the different systems are summarized showing a discrepancy between the intended and the evaluated purpose, and a general lack of validation data confirming a correlation with pain symptoms or quality of life for any of the current systems. A few studies confirm the value of the ENZIAN system for surgical description of deep endometriosis. With regards to infertility, the endometriosis fertility index has been confirmed valid for its intended purpose.

CONCLUSION

Of the 22 endometriosis classification, staging and reporting systems identified in this historical overview, only a few have been evaluated for the purpose for which they were developed. The literature search was limited to PUBMED. Unpublished classification, staging or reporting systems, or those published in books were not considered. It can be concluded that there is no international agreement on how to describe endometriosis or how to classify it, and that most classification/staging systems show no or very little correlation with patient outcomes. This overview of existing systems is a first step in working towards a universally accepted endometriosis classification.

Endometriosis classification, staging and reporting systems: a review on the road to a universally accepted endometriosis classification. Hum Reprod Open 2021;2021:hoab025. [PMID: 34693032 PMCID: PMC8530712 DOI: 10.1093/hropen/hoab025]

STUDY QUESTION

Which endometriosis classification, staging and reporting systems have been published and validated for use in clinical practice?

SUMMARY ANSWER

Of the 22 endometriosis classification, staging and reporting systems identified in this historical overview, only a few have been evaluated, in 46 studies, for the purpose for which they were developed.

WHAT IS KNOWN ALREADY

In the field of endometriosis, several classification, staging and reporting systems have been developed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A systematic PUBMED literature search was performed. Data were extracted and summarized.

MAIN RESULTS AND THE ROLE OF CHANCE

Twenty-two endometriosis classification, staging and reporting systems have been published between 1973 and 2021, each developed for specific, and different, purposes. There still is no international agreement on how to describe the disease. Studies evaluating the different systems are summarized showing a discrepancy between the intended and the evaluated purpose, and a general lack of validation data confirming a correlation with pain symptoms or quality of life for any of the current systems. A few studies confirm the value of the ENZIAN system for surgical description of deep endometriosis. With regards to infertility, the endometriosis fertility index has been confirmed valid for its intended purpose.

LARGE SCALE DATA

NA.

LIMITATIONS, REASONS FOR CAUTION

The literature search was limited to PUBMED. Unpublished classification, staging or reporting systems, or those published in books were not considered.

WIDER IMPLICATIONS OF THE FINDINGS

It can be concluded that there is no international agreement on how to describe endometriosis or how to classify it, and that most classification/staging systems show no or very little correlation with patient outcomes. This overview of existing systems is a first step in working toward a universally accepted endometriosis classification.

STUDY FUNDING/COMPETING INTEREST(S)

The meetings and activities of the working group were funded by the American Association of Gynecologic Laparoscopists, European Society for Gynecological Endoscopy, European Society of Human Reproduction and Embryology and World Endometriosis Society. A.W.H. reports grant funding from the MRC, NIHR, CSO, Wellbeing of Women, Roche Diagnostics, Astra Zeneca, Ferring, Charles Wolfson Charitable Trust, Standard Life, Consultancy fees from Roche Diagnostics, AbbVie, Nordic Pharma and Ferring, outside the submitted work. In addition, A.W.H. has a patent Serum biomarker for endometriosis pending. N.P.J. reports personal fees from Abbott, Guerbet, Myovant Sciences, Vifor Pharma, Roche Diagnostics, outside the submitted work; he is also President of the World Endometriosis Society and chair of the trust board. S.M. reports grants and personal fees from AbbVie, and personal fees from Roche outside the submitted work. C.T. reports grants, non-financial support and other from Merck SA, non-financial support and other from Gedeon Richter, non-financial support from Ferring Pharmaceuticals, outside the submitted work and without private revenue. K.T.Z. reports grants from Bayer Healthcare, MDNA Life Sciences, Roche Diagnostics Inc, Volition Rx, outside the submitted work; she is also a Board member (Secretary) of the World Endometriosis Society and World Endometriosis Research Foundation, Research Advisory Board member of Wellbeing of Women, UK (research charity), and Chair, Research Directions Working Group, World Endometriosis Society. The other authors had nothing to disclose.

TRIAL REGISTRATION NUMBER

NA.

Endometriosis classification, staging and reporting systems: a review on the road to a universally accepted endometriosis classification

Background

In the field of endometriosis, several classification, staging and reporting systems have been developed. However, endometriosis classification, staging and reporting systems that have been published and validated for use in clinical practice have not been systematically reviewed up to now.

Objectives

The aim of the current review is to provide a historical overview of these different systems based on an assessment of published studies.

Materials and Methods

A systematic Pubmed literature search was performed. Data were extracted and summarised.

Results

Twenty-two endometriosis classification, staging and reporting systems have been published between 1973 and 2021, each developed for specific and different purposes. There is still no international agreement on how to describe the disease. Studies evaluating different systems are summarised showing a discrepancy between the intended and the evaluated purpose, and a general lack of validation data confirming a correlation with pain symptoms or quality of life for any of the current systems. A few studies confirm the value of the Enzian system for surgical description of deep endometriosis. With regards to infertility, the endometriosis fertility index has been confirmed valid for its intended purpose.

Conclusions

Of the 22 endometriosis classification, staging and reporting systems identified in this historical overview, only a few have been evaluated, in 46 studies, for the purpose for which they were developed. It can be concluded that there is no international agreement on how to describe endometriosis or how to classify it, and that most classification/staging systems show no or very little correlation with patient outcomes.

What is new?

This overview of existing systems is a first step in working towards a universally accepted endometriosis classification.

Prevalence of Deep Endometriosis and Rectouterine Pouch Obliteration in the Presence of Normal Ovaries

OBJECTIVE

It is well-established that there is a strong association between ovarian endometriomas (OE) and deep endometriosis (DE) and rectouterine pouch (RP) obliteration. We aimed to determine the prevalence of DE and RP obliteration in the presence of normal ovaries.

METHODS

We conducted a multicentre retrospective cohort study from January 2009 to December 2017 using a prospective multicentre data registry. Participants included patients with signs and/or symptoms of endometriosis who underwent excisional laparoscopic surgery at one of eight hospitals. The primary outcome was the prevalence of DE and RP obliteration, which was compared between women with normal ovaries (i.e., no OE) and women with ovaries containing OE. Secondary outcomes evaluated included rates of DE by anatomic site between women with and without OE.

RESULTS

The ovaries did not contain an OE in 319 of 410 patients (77.8%). The prevalence of DE and RP obliteration in this cohort was 25.4% and 9.7% (81 and 31 patients), respectively; whereas, in patients with OE, DE and RP obliteration prevalence was 68.1% and 60.4% (62 and 55 patients), respectively (P < 0.001 for both DE and RP obliteration). The uterosacral ligaments were the most common site for DE (right: 47/319 [14.7%]; left: 42/319 [13.2%]).

CONCLUSIONS

In patients who visited a tertiary care centre with endometriosis without ovarian involvement, 1 in 4 had DE and 1 in 10 had RP obliteration. These prevalence rates should encourage knowledge and skills dissemination to improve non-invasive imaging diagnosis overall. In patients with symptoms or signs suggestive of endometriosis, a basic pelvic ultrasound that ends at evaluation for OE should not be regarded as reassuring.

Transvaginal US of Endometriosis: Looking Beyond the Endometrioma with a Dedicated Protocol

Transvaginal sonography (TVS) is a valuable primary imaging tool for the initial evaluation and management of endometriosis, a complex multifocal disease process with a varied spectrum of clinical and morphologic features that can substantially affect quality of life. The high accuracy of TVS for the detailed mapping of disease extent, an essential process for guiding treatment strategies, is well documented. The dynamic nature of US provides added value, revealing information that is not easily addressed with other imaging modalities. As recognized by the International Deep Endometriosis Analysis Consensus Group, a dedicated standardized protocol that is used by experienced and knowledgeable operators is necessary for a complete evaluation. The four components of a dedicated TVS protocol for evaluation of pelvic endometriosis are (a) evaluation of the uterus and adnexa, (b) dedicated search for deep infiltrating endometriosis, (c) assessment of the sliding sign, and (d) detection of sonographic soft markers. These components are described, and the multiple locations and US findings of endometriosis within the pelvis are reviewed, with emphasis on the unique features of US as an extension of the physical examination. In addition to enabling evaluation of the static findings of adenomyosis, endometrioma, hydrosalpinx, hematosalpinx, and hypoechoic nodules of deep infiltrating endometriosis, dynamic TVS enables assessment of pouch of Douglas obliteration, organ mobility, and site-specific tenderness, as well as tenderness-guided imaging. The benefits of implementing a dedicated TVS protocol in terms of improved patient care are also discussed. Online supplemental material is available for this article. ^©RSNA, 2019.

A Multicenter International Temporal and External Validation Study of the Ultrasound-based Endometriosis Staging System

STUDY OBJECTIVE

The aim of this study was to validate temporally and externally the ultrasound-based endometriosis staging system (UBESS) to predict the level of complexity of laparoscopic surgery for endometriosis.

DESIGN

A multicenter, international, retrospective, diagnostic accuracy study was carried out between January 2016 and April 2018 on women with suspected pelvic endometriosis.

SETTING

Four different centers with advanced ultrasound and laparoscopic services were recruited (1 for temporal validation and 3 for external validation).

PATIENTS

Women with pelvic pain and suspected endometriosis.

INTERVENTIONS

All women underwent a systematic transvaginal ultrasound and were staged according to the UBESS system, followed by classification of laparoscopic level of complexity according to the Royal College of Obstetricians and Gynaecologists (RCOG) levels 1 to 3.

MEASUREMENTS AND MAIN RESULTS

UBESS I, II, and III were then correlated with RCOG levels 1, 2, and 3, respectively. A comparison between temporal and external sites (skipping "A") and between each site was performed in terms of the diagnostic accuracy of UBESS to predict RCOG laparoscopic skill level. A total of 317 consecutive women who underwent laparoscopy with suspected endometriosis were included. Complete transvaginal ultrasound and laparoscopic surgical outcomes were available for 293/317 (92.4%). At the temporal site, the accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of UBESS I to predict RCOG level 1 were 80.0%,73.8%, 94.9%, 97.2%, 60.2%, 14.5%, and 0.3%, respectively; of UBESS II to predict RCOG level 2 were 81.0%, 70.6%, 82.0%, 26.7%, 96.8%, 3.9%, and 0.3%, respectively; of UBESS III to predict RCOG level 3 were 91.0%, 85.7%, 92.4%, 75.0%, 96.1%, 11.3%, and 0.2%, respectively. At the external sites, the results of UBESS I to predict RCOG level 1 were 90.3%, 92.0%, 88.4%, 90.2%, 90.5%, 7.9%, and 0.1% respectively; UBESS II to predict RCOG level 2 were 89.2%, 100.0%, 88.5%, 37.5%, 100.0%, 8.7%, and 0.0%, respectively; and UBESS III to predict RCOG level 3 were 86.0%, 67.6%, 98.2%, 96.2%, 82.1%, 37.8%, and 0.3%, respectively. When patients requiring ureterolysis (i.e., RCOG level 3) in the absence of bowel endometriosis were excluded (n = 54), the sensitivity of UBESS III to correctly classify RCOG level 3 increased from 85.7% to 96.7% at the temporal site (n = 42) and from 67.6% to 96.0% at the external sites (n = 12) (p <.005).

CONCLUSION

The results from this external validation study suggest that UBESS in its current form is not generalizable unless there is either or both bowel deep endometriosis and cul-de-sac obliteration present. The major limitation appears to be the misclassification of women who require surgical ureterolysis in the absence of bowel endometriosis.