Introduction
An ideal classification system should meet three core principles: it should be simple, allow description of the disease and correlate with clinical findings (1). Currently, the two most used classifications systems for endometriosis are the rASRM (2) and Enzian (3), of which neither shows strong clinical correlation with pain symptoms (4, 5). This could be explained by the fact that the rASRM is not directly suitable to describe deep endometriosis (6). On the other hand, the Enzian classification is not able to describe the tubes, ovaries and peritoneum which is covered by the rASRM classification. An attempt to overcome these difficulties has recently been made by theStiftung Endometriose Forschung (SEF) at their annual Weisensee endometriosis meeting, during which an update of the Enzian classification was created: the #Enzian (7).