To predict the difficulty of endometriosis surgery using the #Enzian (u) classification based on preoperative sonography.

A retrospective analysis was conducted on 229 patients with surgically confirmed endometriosis treated at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine between January 2018 and June 2023. The patients were divided into a difficult surgery group (n=93) and a non-difficult group (n=136) based on operative time and blood loss volume. #Enzian (u) and #Enzian (s) classification features, as well as American Society for Reproductive Medicine (ASRM) score, were compared. Binary logistic regression was performed to identify independent predictors of difficult surgery, and regression equations were developed. Receiver operating characteristic (ROC) curves were plotted to analyze the area under the curve (AUC) for the three models [#Enzian (u), #Enzian (s), and ASRM].

For #Enzian (u), the difficult surgery group had significantly higher values for maximum diameter of adenomyosis, maximum diameter of lesions in the FB/FU compartment (bladder and ureter), and grade of compartment C (lesions located up to 16 cm from the anal verge), while the maximum diameter of ovarian endometriosis was smaller in the difficult group compared to the non-difficult group (all P＜0.05). Logistic regression identified grade of compartment C, sum of grades in bilateral compartment T (tubo-ovarian condition), maximum diameter of lesions in FB/FU, maximum diameter of adenomyosis, and maximum diameter of ovarian endometriosis as independent predictors of surgical difficulty (all P＜0.05). The AUC of the regression equation was 0.733 (95% confidence interval [CI]: 0.666~0.799, P＜0.001). For #Enzian (s), the difficult surgery group showed higher grades of compartment P (peritoneum), compartment Tr (right tubo-ovarian condition), and compartment C, as well as a higher proportion of adenomyosis compared to the non-difficult group (all P＜0.05). Logistic regression indicated that grade of compartment C, sum of grade in bilateral compartment T, and presence of adenomyosis were independent predictors of surgical difficulty (all P＜0.05). The AUC of this regression equation was 0.752 (95%CI: 0.687~0.816, P＜0.001). The diagnostic performance of both #Enzian-based equations outperformed that of the ASRM score (AUC=0.671).

The #Enzian (u) classification is useful for preoperatively predicting the difficulty of endometriosis surgery. It provides valuable guidance for enhanced preoperative planning, improved surgeon–patient communication, and postoperative management.