Patient- and disease-related characteristics to anticipate segmental resection for isolated rectal endometriosis: a multicenter prospective study.

STUDY OBJECTIVE: To identify predictors for segmental resection in patients with an isolated rectal endometriotic nodule (i.e. involvement of at least the muscular layer in depth and up to 15cm to the anus). DESIGN: Multicenter prospective observational study evaluating 5 predefined predictors: bowel endometriosis syndrome (BENS) score, rectal nodule characteristics (length on ultrasound; height and circumference on MRI) and prior surgery in the rectovaginal space/bowel. SETTING: Two European referral centers: University Hospitals Leuven (Belgium) and Semmelweis University Hospital in Budapest (Hungary). PARTICIPANTS: 196 patients with rectal endometriosis were included: 104 (53.1%) underwent segmental resection and 92 (46.9%) had conservative surgical treatment. INTERVENTIONS: Laparoscopic surgery for rectal endometriosis using either a radical approach (with colorectal segmental resection) versus a more conservative approach aiming at preserving the rectal ampulla (by shaving or disc excision). MEASUREMENTS AND MAIN RESULTS: Uni- and multivariable logistic regression models, including the five predefined predictors as well as center of inclusion. Of these, only rectal nodule length on ultrasound (in mm) and MRI circumference (affected % of the outer contour) were associated with segmental resection. Rectal nodule length was 19.1±9.2mm in the conservative vs 25.8±11.9mm in the segmental resection group (p<0.001), MRI circumference was respectively 26.0±10.0% and 35.4±11.1% (p<0.001). Results of the multivariable regression model (only considering rectal nodule length and MRI circumference) confirm the importance of these two factors: odds ratio (OR) of 1.047 (95%CI 1.010-1.085; p=.0123) for the rectal nodule length and OR of 4.543 (95%CI 2.276-9.068; p<.001) for the (log2-transformed) MRI circumference. The discriminative ability (AUC) equaled 0.756 (0.688;0.824). CONCLUSION: Given that rectal nodule length and circumference have been identified as important predictors for the type of surgery, we propose to systematically evaluate them preoperatively to support surgical planning and patient counseling.