Endometriosis is a common disease with endometriotic lesions being found in the ovaries, peritoneum, or as deep endometriosis (DE) involving different pelvic organs and structures. In order to describe DE lesions, the Enzian classification was developed. In the last revision of this Enzian classification, the so-called #Enzian, presence and severity grades of ovarian and peritoneal endometriosis as well as adhesions involving tubes and ovaries are also described in addition to DE lesions.

The Enzian classification is determined intraoperatively by the surgeon. Transvaginal ultrasound (TVS) examination is considered to be the first-line imaging technique for this disease. Therefore, the aim of this study is to compare the assessment of presence and severity grade of endometriotic lesions in different Enzian compartments by a preoperative ultrasound examination (in the form of an US-Enzian classification) to the definitive intraoperative Enzian classification (OP-Enzian) using the latest revision of the Enzian classification (Enzian).