Inclusion Criteria:  Patients who consent to use their data in this study Patients with endometriosis diagnosed by transvaginal ultrasound (TVUS) and/or MRI Patients undergoing fertility-preserving surgery Patients with pain due to endometriosis Patients with endometriotic lesions other than ovarian cysts confirmed by MRI (concomitant ovarian cysts can be recruited) Patients with the following patient clinical information (TVUS is not mandatory when archived data is used)  Patient clinical information: Preoperative MR images, videos of laparoscopic surgery, pathological evaluation of endometriosis, videos of preoperative TVUS, pain information related to endometriosis, information about infertility before surgery, information on QOL, information on postoperative recurrence, information on surgical difficulty, operating time, length of hospital stay for surgical operation, age, history of treatment (drugs, surgery), anamnesis and complication, history of endometriosis, age at menarche, menstrual cycle, date of surgery, date of MR image acquisition, operative procedure and history of pregnancy and childbirth.  Exclusion Criteria:  Patients who had surgery for endometriosis prior to the surgery included in this study Patients deemed inappropriate by the principal investigator Patients who obtained their voluntary consent but later withdrew their consent