OBJECTIVE: To assess the diagnostic performance of preoperative application of the Enzian classification (cEnzian) using surgical findings as reference standard. DESIGN: A prospective international non-interventional study. SETTING: Twelve endometriosis centres in four European countries (Austria, Germany, Switzerland and Czech Republic). POPULATION: 1062 women with endometriosis surgery. METHODS: Extent of endometriosis was preoperatively classified using the cEnzian classification based on gynaecological examination and/or transvaginal ultrasound (TVS) and/or magnetic resonance imaging (MRI). After subsequent surgery, the surgeon classified the intraoperative findings using the Enzian classification. MAIN OUTCOME MEASURES: Sensitivity, specificity, PPV, NPV, LR+ , LR- and accuracy were calculated. Conditional frequencies of intraoperative Enzian codings and the corresponding 95% confidence intervals were computed for each preoperative coding and visualised in plots. RESULTS: Although overall consistency of cEnzian and Enzian was poor (35.14%, 95% confidence interval 32.26-38.03), high specificities and negative predictive values (NPVs) of the cEnzian compartments could be demonstrated. Looking at the individual parts of the Enzian classification, the poorest diagnostic performance was detected for compartment B and the highest PPVs were found for category 3 lesions (>3 cm), independent of the compartment. CONCLUSIONS: Using the Enzian classification in a non-invasive setting is a useful tool providing us with an 'at a glance' summary of the diagnostic workup regarding deep endometriosis with high specificities and NPVs. An attempt to merge the two new endometriosis classification systems (#Enzian and AAGL 2021) seems reasonable taking into consideration the respective advantages of each other.

Center for Clinical Studies Johannes Kepler University Linz Linz Austria

Department Gynaecology and Obstetrics Hanover Medical School Hannover Germany

Department of Gynecologic Endocrinology and Reproductive Medicine Medical University of Innsbruck Innsbruck Austria

Department of Gynecology and Obstetrics Johanniter Krankenhaus Mönchengladbach Mönchengladbach Germany

Department of Gynecology and Obstetrics Landesklinikum Melk Melk Austria

Department of Gynecology and Obstetrics St Johannes Hospital Dortmund Germany

Department of Gynecology and Obstetrics University Hospital Carl Gustav Carus Dresden Germany

Department of Gynecology and Obstetrics University Hospital Münster Münster Germany

Department of Gynecology Obstetrics and Gynecological Endocrinology Kepler University Hospital Johannes Kepler University Linz Linz Austria

Department of Gynecology Obstetrics and Gynecological Oncology Bethesda Hospital Academic Teaching Hospital Duisburg Germany

Department of Gynecology University Hospital Tübingen Tübingen Germany

Department of Obstetrics and Gynecology University Hospital and University of Bern Bern Switzerland

Institute for the Care of Mother and Child Prague Czech Republic

Institute of Applied Statistics Johannes Kepler University Linz Linz Austria

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