OC09.03: Identification and characteristics of deep endometriosis infiltrating the sacral plexus with transvaginal ultrasound

To assess whether routine examination of the sacral plexus (SP) on transvaginal sonography (TVS) can identify nerve involvement by deep endometriosis (DE) and should therefore be recommended in all patients with DE. Prospective single, tertiary referral-centre observational study including consecutive women undergoing TVS for clinically suspected pelvic DE before laparoscopic surgery, between January 2020 and February 2023 at Semmelweis University, Budapest, Hungary. TVS and gynecological examination were performed within 2 months before surgery, preoperative TVS signs were analysed and compared with laparoscopic and histological findings The main outcome of interest was the presence of infiltration of the SP by DE. Of the 797 consecutive patients scheduled for surgery with DE, 22 women were not tolerating TVS on the SPs, 3 patients were not consenting participation in the study, and by one woman Tarlov cyst was diagnosed by MRI prior to TVS. The remaining 771 patients were enrolled in the study. Among them DE associated SP infiltration was diagnosed on TVS in 15 (1.9%) cases. SP involvement was confirmed intraoperatively in all 15 cases and verified histologically. DE lesions infiltrating the SP were hypoechoic nodules of the parametrium and the uterosacral ligaments with a median diameter of 33 mm (range, 23–45 mm). Of the 15 lesions 8 were on the right side, and 7 on the left side. The following spinal nerves were involved: S1 (8/15) S2 (13/15) S3 (8/15) S4 (3/15). At one patient the lumbosacral trunc and by another woman the right obturator nerve was also infiltrated. Associated DE in extragenital organs was found: rectum (10/15), ipsilateral ureters (7/15), bladder (6/15). TVS examination is reliable diagnostic tool for the detection of SP involvement by DE. Applying TVS, DE is encountered in this location in 1-2% of women attending tertiary referral centres for suspected pelvic DE. Associated DE lesions in the rectum and in the urinary tract are frequent.