Objective-To develop a model using individual and lesion characteristics to help surgeons choose lesions with a high probability of containing histologically-confirmed endometriosis.Design-Secondary analysis of prospectively collected information. Setting: Government research hospital.Patients-Healthy women aged 18-45 with chronic pelvic pain and possible endometriosis, enrolled in a clinical trial.Intervention-All participants underwent laparoscopy, and information was collected on all visible lesions. Lesion data were randomly allocated to a training and test dataset.
Main Outcome Measures(s)-Predictive logistic regression with the outcome of interest being histologic diagnosis of endometriosis.Results-After validation, the model was applied to the complete dataset with a sensitivity of 88.4% and specificity of 24.6%. The positive predictive value was 69.2% and the negative predictive value was 53.3%, equating to correct classification of a lesion of 66.5%. Mixed color, larger width and location in the ovarian fossa, colon, or appendix were most strongly associated with the presence of endometriosis.Conclusions-This model identified characteristics which indicated a high and low probability of biopsy-proven endometriosis. It is useful as a guide in choosing appropriate lesions for biopsy, but is not sufficiently robust to use alone.