VP62.35: Can we predict the revised American Fertility Society stage using the preoperative transvaginal ultrasound based endometriosis staging system in women with suspected endometriosis? A retrospective observational study

The pre-operative transvaginal ultrasound based endometriosis staging system (UBESS) has been demonstrated to predict surgical skill level required for laparoscopic endometriosis surgery. This study aimed to determine whether UBESS can also be used to predict revised American Fertility Society (r-AFS) classification in women undergoing laparoscopy for suspected endometriosis. This was a retrospective observational study conducted at Liverpool Hospital between October 2019 and January 2020. Clinical and surgical data was collected for women who underwent pre-operative TVU followed by laparoscopic surgery for suspected endometriosis. Women were assigned a UBESS level from I-III, depending on TVU findings. UBESS I(mild stage disease), II(moderate stage disease) and III(higher stage disease) were then correlated with the r-AFS stage I-IV at laparoscopy. UBESS I was correlated with r-AFS I/II stage, UBESS II was correlated with r-AFS III stage (no bowel deep endometriosis or POD obliteration), and UBESS III was correlated with r-AFS IV (including bowel deep endometriosis and/or POD obliteration). Complete TVU and surgical data was available for 44 women. The age range was from 18-49 years. Incidence of r-AFS stage was as follows: I = 24/44(55%), II = 2/44(5%), III = 6/44(14%), and IV = 12/44(27%). The sensitivity, specificity, positive predictive value, and negative predictive value for UBESS I for the prediction of r-AFS stage I/II was 75%, 85%, 86%, and 74%, respectively. UBESS level II for r-AFS stage III was 22%, 77%, 40%, and 59%, respectively; and for UBESS level III and r-AFS stage IV was 100%, 97%, 92%, and 100%, respectively. UBESS appears to perform well for the prediction of minimal/mild (r-AFS I/II) and especially well for severe stage (r-AFS IV) disease, but had a low sensitivity and positive predictive value for moderate stage (r-AFS III) disease.