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 ( = 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 Interests: No financial support was specifically received for this study. The authors declare no conflict of interest.

Trial Registration Number: N/A.