OC19.03: Modified ultrasound‐based endometriosis staging system and CA125 endometriosis severity prediction model

The modified ultrasound-based endometriosis staging system (M-UBESS) and Ca-125 endometriosis severity prediction model aims to incorporate transvaginal ultrasound (endometrioma, POD obliteration, ovarian fixation, uterosacral ligament(USL) endometriosis) and biochemical (Ca-125) markers to improve the prediction of intraoperative ureterolysis and isolated peritoneal disease, thereby improving the UBESS accuracy in predicting surgical complexity. Prospective diagnostic accuracy study (Jan 2020-May 2021), including 74 women who underwent laparoscopic endometriosis surgery. Preoperative Ca-125 and 5-domain transvaginal ultrasound was performed for all women prior to surgery. Preoperative M-UBESS stage and CA-125 levels were correlated with r-ASRM stage and AGES (Australasian Gynecological Endoscopy and Surgery) laparoscopic skill level, including the need for ureterolysis. Clinical and surgical data was available for 74 women. M-UBESS accuracy in predicting generalist/advanced laparoscopic skill level was 69%(p = 0.02)/78%(p = 0.001), and for r-ASRM stages I-II// III-IV was 64%(p = 0.03)/85%(p = 0.001). Ovarian endometrioma/POD obliteration/USL endometriosis/ovarian fixation predicted the need for ureterolysis with the following accuracy: 78%(p = 0.006)/80%(p = 0.002)/74%(p = 0.08)/51% (p = 0.3), respectively. CA-125 (<30) predicted r-ASRM stage I/II and generalist AGES skill level in 73%(p = 0.02) and 45%(p = 0.3), respectively. This threshold was able to distinguish between nil disease and r-ASRM I-II (sensitivity 75%) as well as identify those with pelvic side wall endometriosis (sensitivity 74%), at risk of requiring ureterolysis. Incorporation of TVU features such as endometrioma, POD obliteration, USL endometriosis and ovarian fixation, as well as the CA-125 biochemical marker, appear to improve the prediction of intraoperative ureterolysis and isolated peritoneal disease in women with suspected endometriosis.