Endometriosis is considered to be a frequent, chronic inflammatory disease which can cause infertility as well as different pain symptoms such as chronic pelvic pain, dysmenorrhea, dyschezia, dysuria, and dyspareunia. Endometriotic lesions can be found as superficial peritoneal implants or ovarian cysts and may cause filmy or dense adhesions. Deep infiltrating endometriosis (DIE), which represents a severe form of the disease, is characterized by the infiltration of different anatomic structures such as the bowel, ureters or the urinary bladder by endometriotic tissue.
Over the past decades, numerous attempts have been made to create an adequate, clinically useful and internationally accepted classification system in order to allow for an easy and uniform description and staging of the disease. Furthermore, the use of appropriate scores is pivotal to have a standardized basis to conduct and compare international studies on endometriosis. Most of the classification systems are surgical scores which are mainly based on the anatomic localization and extent of endometriotic lesions and associated adhesions as determined by surgical exploration. To date, the most widely used and recognized classification of endometriosis is the revised American Society for Reproductive Medicine (rASRM) score. Over the past years, the ENZIAN score for the description of DIE has gained increasing attention and acceptance and is increasingly used in combination with the rASRM score.
The rASRM score
The rASRM score differentiates 4 stages of the disease according to the extent of peritoneal lesions, endometriotic lesions of the ovaries, posterior cul-de-sac obliteration and associated adhesions: stage I—minimal, stage II—mild, stage III—moderate, and stage IV—severe1. However, the localization and extent of DIE lesions, which may affect the bowel, the uterosacral ligaments, the urinary bladder, the ureters, the rectovaginal septum, and/or the pouch of Douglas with complete or partial obliteration, are not fully taken into account by the rASRM score. This discrepancy is mainly caused by the fact that rASRM stages increase directly with the extent of adhesions which do not necessarily correlate with the presence or absence of DIE. Although DIE is partly taken into account by the rASRM, the score does not provide the clinician with the possibility to describe the extent and exact anatomic localization of DIE. As determined by various studies, the extent of endometriosis described by the rASRM stages only shows poor correlations with the presence and severity of different pain symptoms as well as with infertility2–5.
The revised ENZIAN score
The need for an appropriate description of DIE lesions which are not addressed by the rASRM score led to the development of the ENZIAN classification in addition to the rASRM score in 20036,7. After its revision in 2010 and 2011, the revised ENZIAN score distinguishes the following different intraoperatively determined anatomic localizations of DIE lesions: ENZIAN compartment A (vagina, rectovaginal septum); compartment B (uterosacral ligaments, parametrium); compartment C (rectum, sigmoid colon); compartment FA (adenomyosis); compartment FB (urinary bladder); compartment FU (intrinsic involvement of the ureters), compartment FI (intestine), and compartment FO (other localizations)8 (Fig. 1). Furthermore, deep endometriotic lesion size is described as severity grade 1: <1 cm; grade 2: 1–3 cm; grade 3: >3 cm for each of the compartments A, B, and C8 (Fig. 1).
Considering the poor correlation of rASRM stages with presence and/or severity of different pain symptoms, possible associations between the localization of DIE lesions as described by the revised ENZIAN score and endometriosis-related symptoms were evaluated. In this regard, a partial correlation of the revised ENZIAN score with clinical symptoms was shown by a study with limited patient numbers, where dysmenorrhea and dyspareunia were found to be associated with adenomyosis (ENZIAN compartment FA) and bowel symptoms were associated with lesions in ENZIAN compartment C (rectum and sigmoid colon)9.
Recent evidence analyzing data of 245 women who underwent surgical treatment for DIE demonstrated that the presence of different pain symptoms was indeed associated with the presence of endometriotic lesions in certain ENZIAN compartments. Furthermore, symptom severity correlated significantly with lesion size as described by the intraoperatively determined revised ENZIAN score10. In detail, dyschezia was associated with both involvement of ENZIAN compartment A as well as with infiltration of compartment C. Dyspareunia was found to be associated with the presence of DIE in compartment B and dysuria with involvement of compartment FB. Furthermore, symptom severity of different pain symptoms, expressed on a 10-point visual analogue scale (VAS), significantly correlated with the size of DIE lesions in certain ENZIAN compartments. Namely, the severity of dysmenorrhea with lesion size in both compartment A and C and severity of dyschezia with lesion size in both compartment A and C. In addition, higher VAS values for dysmenorrhea were found in women with adenomyosis. As pain symptom severity in women with DIE might represent a cumulative effect of individual DIE lesions rather than the mere consequence of the involvement of a single compartment, resulting symptom severity may be greater or lesser than expected. In this regard, especially the severity of dysmenorrhea, but also of dyschezia, correlated with the total number of affected ENZIAN compartments (when taking into account compartments A, B, C, and FA). In contrast, and in line with previous studies, no correlation was found between the intensity of the evaluated symptoms and rASRM stages.
Taken together, for an accurate staging of the disease, the available data underline the need to use the revised ENZIAN score for the assessment of DIE lesions in addition to the rASRM score, which mainly takes into account peritoneal lesions and adhesions.
Future perspectives—the # ENZIAN
Taken together, accurate staging of endometriosis, especially DIE appears to be facilitated with the additional use of the revised ENZIAN score. A recent and last revision of this score was developed at the beginning of 2019 and now includes the possibility to describe the extent of peritoneal and ovarian endometriosis as well as the condition of the fallopian tubes with regard to fertility11, so that endometriosis could be described with a single classification. The so-called #ENZIAN aims to provide the surgeon but also radiologists and sonographers with a tool to speak a uniform language when describing endometriosis.
Conflict of interest disclosures
The authors declare that they have no financial conflict of interest with regard to the content of this report.
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