Negative Sliding Sign during Dynamic Ultrasonography Predicts Low Endometriosis Fertility Index at Laparoscopy

STUDY OBJECTIVE: Endometriosis fertility index (EFI) is a robust tool to predict the pregnancy rate in patients with endometriosis who are attempting non-in vitro fertilization conception. However, EFI calculation requires laparoscopy. Newly established imaging techniques such as sliding sign, which is used to diagnose pouch of Douglas obliteration, could provide a promising alternative. The objective of this study was to investigate the practicality of using ultrasound data to predict a low EFI (score ≤6). DESIGN: Observational study from a prospective registry (Endometriosis Pelvic Pain Interdisciplinary Cohort, clinicaltrials.gov #NCT02911090). Analyzed data were captured from December 2013 to June 2017. SETTING: Tertiary referral center at British Columbia Women's Hospital. PATIENTS: We analyzed data for 2583 participants from the Endometriosis Pelvic Pain Interdisciplinary Cohort. In this cross-sectional study, we included 86 women aged <40 years. INTERVENTIONS: Dynamic ultrasonography for the sliding sign testing and EFI calculation during laparoscopic surgery. MEASUREMENTS AND MAIN RESULTS: Logistic regression was used to obtain receiver operating characteristic area under the curve (AUC) for the prediction models. Significance was p <.05. Patients with a negative sliding sign were older and had severe endometriosis and longer duration of infertility. Patients with a negative sliding sign had significantly lower total EFI scores and lower surgical factors scores than patients with a positive sliding sign. Logistic regression showed that a negative sliding sign and EFI historic factors score can predict an EFI score ≤6 (sensitivity = 87.9%, specificity = 81.1%, AUC = 0.93 [95% confidence interval, 0.88-0.98]). Adding the diagnosis of endometrioma to the previous prediction model resulted in AUC = 0.95 (95% confidence interval, 0.90-0.995), sensitivity = 84.8%, and specificity = 92.5%. CONCLUSION: The sliding sign could be a potential alternative to the EFI surgical factors, and it could be used in combination with EFI historic factors and the diagnosis of endometrioma to predict an EFI score ≤6 for patients who are not scheduled for immediate surgery.