ENDORECT: a preoperative score to accurately predict rectosigmoid involvement in patients with endometriosis

STUDY QUESTION: Could we construct and validate a preoperative score to predict rectosigmoid involvement in endometriosis (RE)? SUMMARY ANSWER: We developed a simple preoperative score (ENDORECT) to predict RE. WHAT IS KNOWN ALREADY: Accurate preoperative classification is important to optimize the surgical approach for patients with endometriosis but there is currently no reliable first-line examination to determine RE. STUDY DESIGN, SIZE, DURATION: This was a single-centre observational study including all women (N = 119) who underwent complete surgery for endometriosis between January 2011 and June 2016 in the Gynaecological Department of the University Hospital of Poissy Saint-Germain en Laye. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of the 119 women, 47 had RE and 72 did not. Two-thirds of the patients were randomly selected to derive the predictive score based on multiple logistic regression with internal validation by bootstrap. We used information from a self-assessment questionnaire, digital and speculum examination, transvaginal ultrasound and MRI. The score was then applied to the remaining sample of patients for validation. MAIN RESULTS AND THE ROLE OF CHANCE: Four variables were independently associated with RE: palpation of a posterior nodule on digital examination (aOR=5.6; 95%CI [1.7–21.8]); a UBESS score of 3 on ultrasonography (aOR=4.9; 95%CI [1.4–19.8); RE infiltration on MRI (aOR=6.8; 95%CI [2–25.5]); and presence of blood in the stools during menstruation (aOR=5.2; 95%CI [1.3–24.7]). The ROC-AUC of the model was 0.86 (95%CI [0.77–0.94]) and the bootstrap procedure showed that the model was stable. The ENDORECT score was derived from these four criteria and three risk groups were identified: the high-risk group (score>17) had a probability of RE of 100% with an specificity (Sp) of 100%, postive likelihood ratio (Lr+)>10; the intermediate-risk group (score: 7–17) had a probability of RE of 42%; and the low-risk group (score=0), with a sensitivity (Se) of 97%, negative likelihood ratio (Lr-) of 0.07 and a probability of RE of 5%. In the validation cohort, a score >17 predicted RE with an Sp of 96, Lr+ of 9.2, and probability of RE of 83%. Patients in this sample with a score=0, had an Se of 100%, Lr- of 0 and a probability of RE of 0%. LIMITATIONS, REASONS FOR CAUTION: The single-centre recruitment and over-representation of RE could constitute a referral bias. WIDER IMPLICATIONS OF THE FINDINGS: The use of a preoperative predictive score could facilitate patient counselling and guide surgical management. Both MRI and transvaginal ultrasound provide independent information and are useful before surgery for RE. STUDY FUNDING/COMPETING INTEREST(S): No financial support was specifically received for this study. The authors declare no conflict of interest TRIAL REGISTRATION NUMBER: N/A.