Endometriose, Ultraschall und #Enzian-Klassifikation: Die Notwendigkeit einer gemeinsamen Sprache für die nicht invasive Diagnostik

Endometriosis is a benign disease with a wide variety of manifestations and symptoms, which primarily affects women of childbearing age and in some cases has a fundamental and permanent impact on their quality of life. Although the genesis is still unclear despite a wide variety of explanatory models, we know that the disease can have a progressive character and that diagnosis is not infrequently made far too late, which can have devastating consequences for the woman. The mechanism underlying this problem is multifactorial, but the most likely factor is the persistent belief that the diagnosis can only be made by surgery. Transvaginal ultrasonography (TVS) is the standard diagnostic procedure used by gynecologists. While it was previously clear that this could accurately visualize ovarian endometriosis, there is increasing recognition that transvaginal ultrasound (TVS) can also reliably diagnose deep endometriosis (DE) [1] [2] [3] [4] [5]. This includes all important structures of the internal genital tract (vagina, uterus, ovary, tube, ligamentous structures) [1] [6] [7], and especially the visualization of adenomyosis [8] [9] [10]. In addition, all other anatomical structures of the pelvis with the various compartments including the extragenital organs (bladder, bowel, ureter) [11] [12] [13] and the connective tissue support structures can be sonographically well depicted and their infiltration by endometriosis can be differentiated. A structured system, such as the IDEA [14] or MUSA [15] criteria, is very helpful for the evaluation of the pelvis and documentation including classification. The sometimes very high sensitivity and specificity depends on the one hand on the organs to be examined and the size of the findings and on the other hand on the examination setting (expertise of the examiner and technical requirements).

Extrapelvin localized endometriosis lesions can be additionally visualized by transabdominal ultrasound and, if necessary, by an additional MRI examination as a 2nd important non-invasive procedure.

The question of which of the procedures, TVS or MRI, should be used as a priority is currently the subject of mixed opinion [16]. This depends not only on the procedure itself, but also on the different habits and traditions in gynecological diagnostics of the various societies and countries, and not least on the personal expertise of the clinician.

The advantage of TVS clearly lies in the simplicity of the methodology and universal applicability (practice, operating room, etc.), as well as in the fact that it can be performed by the gynecologist or surgeon himself. The possibility of a dynamic examination (sliding sign, tenderness, etc.) [17] [18] in conjunction with knowledge of the individual symptomatology is very informative and extremely helpful for making a diagnosis and further therapeutic decisions. Specific locations that are difficult to access sonographically (diaphragm, lung, lateral pelvic sidewall) can be better visualized with MRI [19] [20].

In addition to the obvious clinical advantages of transvaginal sonography over MRI, it is also important to consider the significantly lower costs and, in times of climate crisis, the environmental impact. Ultrasound has the lowest values, while magnetic resonance imaging (MRI) has the highest carbon footprint due to its high energy consumption [21].

Whereas diagnostic laparoscopy (LSK) was previously the gold standard for further therapy decisions, ultrasound diagnostics opens up completely new perspectives.

Early accurate diagnosis and compartmental description of the extent and severity of the disease is of great advantage for patient counseling and further treatment planning.

The symptoms described can be assigned to the findings obtained sonographically.

Deep endometriosis, which in some cases cannot be clearly identified in diagnostic laparoscopy, can be completely visualized with TVS in the extraperitoneal space without having to remove it with a risky operation. This is particularly helpful when lesions are not symptomatic and/or do not show progressive growth.

Sonographic observation (by regular checks) of the lesions in the context of conservative therapy allows control of disease dynamics and facilitates the development of individualized therapeutic strategies. In a long-term sonographic study of deep rectal endometriosis, it was shown that these deep foci have a specific growth behavior that depends on both age and hormone treatment, which can be calculated by a statistical model [22].

Prior to surgical intervention, the exact localization and measurement of the DE can be used to predict the duration, complexity but also the risks of surgery. The aim is to avoid unnecessary surgery and to allow a differentiated indication for individual interventions.

In the context of infertility, especially ovarian endometriosis and adhesions, ultrasound helps to decide between ART or surgical therapy.

Clearly, TVUS, when performed by experts, is more accurate than routine pelvic ultrasound in diagnosing endometriosis, especially the non-ovarian form [23].

Transvaginal ultrasonography therefore requires specialized training and expertise in endometriosis diagnosis [24]. The goal is to promote structured good training opportunities and eventually develop certification according to a defined graduated concept.

Patients, especially with severe endometriosis, can be identified at an early stage and, if necessary, referred to centers of excellence with multidisciplinary teams (gynecologists, urologists, surgeons, and reproductive physicians).

The description of endometriosis in the context of noninvasive diagnostics has been mainly in the form of a narrative report, partly structured by recommendations from experts.

Communication between the radiologists, sonographers and the surgeon is thus hindered rather than encouraged.

The rASRM classification has been used mainly to describe endometriosis in the context of diagnostic laparoscopy [24]. This classification is not suitable for non-invasive diagnostics, and does not take deep endometriosis (DE) into account. An essential part of the pathology is missing, which complicates patient counseling and clinical decision making.

For the same reason, the results of scientific papers using this classification are likely to be considered inaccurate and, in some cases, irrelevant. In order to have a common language to describe deep endometriosis, the Enzian classification was developed in 2003 [25]. In 2021, this classification was further developed into the #Enzian classification[26] [27] and presented as a comprehensive system for use in non-invasive and invasive diagnostics. This new classification is very well suited to describe all findings in the pelvis, but also outside the pelvis, in terms of localization and size [28].

The apparent inaccuracy of the ASRM classification is supported by a prospective study comparing the ASRM classification with the #Enzian classification [31]. Reducing very complex findings to only 4 levels, as the ASRM classification does, leads to individual findings not being reproducibly mapped. Even in patients with stage 1, severe pathologic findings were found, especially in the extraperitoneal space or in the rectum. A differentiated and complete documentation of findings by a code, as in the #Enzian classification, corresponds much more to clinical reality.

A correlation between the findings and the symptoms is not present in the ASRM classification, whereas it has been demonstrated in the use of Enzian classification by the study of Montanari et al. [30].

With the differentiated sonographic presentation and detailed description using #Enzian classification, mathematical multifactorial models can be developed to establish correlations and conclusions about findings and symptoms. Prospective studies need to be performed for this purpose.

Similarly, the prediction of fertility in different endometriosis findings [29]. The assessment of relevant endometriosis findings in combination with other fertility-relevant biographical (age, fertility history) and anatomical (tubal status, etc.) information could be calculated analogously to the EFI (Endometriosis Fertility Index) [28]. Corresponding studies are in planning.

Several studies have also been performed demonstrating the advantage of the use of #Enzian classification in sonographic diagnosis. In this issue of the European Journal of ultrasound the retrospective study of Di Giovanni is published [32]. This Italian study with high sonographic and surgical expertise demonstrates the accuracy of classification and the agreement of sonographically classified findings with intraoperative findings. The prospective multicenter study by Montanari et al. [42] was able to confirm Di Giovanniʼs findings in 745 patients.

The results of these studies also show that the new classification can be applied as well as the noninvasive diagnostic method itself. Detection of deep endometriosis in the sacrouterine ligament or in higher bowel segments was dependent on both anatomy and examiner and also demonstrated the need for certain expertise. The depiction of pathologic findings in the lateral pelvic wall, possibly involving nerves such as the sacral plexus, are still undergoing scientific and clinical testing.

The now commonly found language, the #Enzian, has also been evaluated by radiologists and has proven to be a useful tool for describing findings [33] [34] [35].

The #Enzian classification is initially considered difficult to understand by some colleagues. Of course, it is easier to apply a finding with only stages 1–4 than to create a complex code. The ASRM classification is often made by estimation rather than exact assessment. A study by Metzemaeker shows that the application of ASRM classification without the support of a digital registration system leads to an incorrect result in most cases. In a comparison between ASRM, Enzian and EFI, Enzian classification was found to have the highest accuracy [36]. This was even better when the classification was done with a web-based program as with EQUSUM.

With the #Enzian classification, pathological findings of all compartments can be evaluated, coded and documented in detail, which simplifies clinical decisions and also surgical strategies significantly.

Patients often want to know the stage of their disease. It would be easy to give a stage 1–4, but this does not correspond to the character of the disease or the prognosis for the patient. A very detailed depiction and documentation of the disease (code) facilitates both communication with the patient and her understanding of the various localizations of the pathological findings. Especially in patients with few symptoms, a more differentiated description can therefore also be helpful in eliminating fears and uncertainties about the extent of the disease and possible progression.

An App (open access) developed by A. Wattiez (MIS) [37] allows learning how to use the #Enzian classification on a smartphone, which facilitates the recording of the complexity of the classification and the documentation of the collected code. Another App from the Scientific Endometriosis Foundation (SEF) is under development.

The #Enzian classification is currently the most comprehensive system suitable for both non-invasive and invasive diagnosis. The International Society of Gynecological Endoscopy (ISGE) therefore recommends the use of the IDEA criteria in combination with the #Enzian classification in the sonographic diagnosis of DE [38].

The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) and the International Deep Endometriosis Analysis (IDEA) Group, the European Society for Gynaecological Endoscopy (ESGE), the European Endometriosis League (EEL), the International Society for Gynecologic Endoscopy (ISGE), the European Society of Human Reproduction and Embryology (ESHRE), the European Society of Urogenital Radiology (ESUR), and the American Association for Gynecologic Laparoscopists6(AAGL) are currently developing a joint consensus statement with evidence-based statements on the use of noninvasive imaging techniques for the noninvasive diagnosis and classification of endometriosis.

The most recent ESHRE (European Society of Human Reproduction and Embryology) endometriosis guideline [39] puts the requirement for histological (surgical) confirmation of endometriosis diagnosis into perspective. The society recommends, due to the progress and high quality of imaging techniques, a complete reassessment of the indication for surgical diagnosis, which also involves risks. For example, Goncalves et al. [40] show that systematic assessment of endometriosis by transvaginal ultrasound (TVS) can replace diagnostic laparoscopy, especially in cases of deep and ovarian endometriosis.

A shift from surgical or lesion-oriented diagnosis to a more comprehensive diagnosis, in which noninvasive imaging findings play a crucial role in addition to symptoms and signs, allows for the significant reduction of diagnostic delay.

To increase the quality of the methodology and its application in everyday life, special training courses for the special sonographic skills are to be established [41]. The certification of specialists or centers with high sonographic competence is discussed to ensure comprehensive interdisciplinary care of patients with severe diseases.

Summary:

Ultrasound examination in case of suspected endometriosis and in case of manifest endometriosis, is one of the most important pillars in the context of diagnostics, but also in the choice of individual therapy concepts. It gives endometriosis a face and a shape, one gets a very precise idea of the extent of the disease without necessarily having to remove it. It helps to avoid unnecessary operations and improves the planning and management of individual surgical procedures. It also facilitates postoperative follow-up, especially in severe cases.

The application of the #Enzian classification for sonographic examination leads to a systematic description and classification of the disease. This classification is comprehensive and allows both non-invasive and surgical application. This greatly facilitates communication between physicians and patients, sonographers and surgeons, and improves interdisciplinary collaboration.

Publication History

Article published online:
06 June 2023

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