OC19.06: The natural history of non‐ovarian highly vascularised pelvic findings in pregnant women suffering from endometriosis

To describe the natural history of pelvic findings with enhanced vascularity found during pregnancy in women suffering from endometriosis. This is a prospective observational cohort study carried out at a single tertiary centre. Pregnant women with histological or clinical diagnosis of endometriosis were consecutively recruited over a period of 18 months, and underwent pelvic ultrasound every 2-3 months and after delivery. Ultrasound examination and Doppler quantitative assessment of blood flow were conducted according to IDEA protocol, with some adjustments for pregnancy. Findings that were judged to be endometriosis on the basis of subjective assessment were recorded. Between December 2018 and May 2020, 24 women were recruited to the study. Endometriosis was histologically confirmed in 14/24 (58%), suspected by ultrasound in 7/24 (29%) (6 endometriomas with or without deep nodules and one rectal nodule) and clinically suspected in 3/24 (13%). During pregnancy, findings that were considered to be endometriosis nodules were observed in 13 women (54%) and Doppler showed enhanced vascularity that may mimic malignancy in eight (33%). Six out of the eight vascularised lesions were found in histologically confirmed cases and two in ultrasound suspected cases. Twelve women (50%) with three vascularised findings were examined after delivery. Two of the vascular lesions resolved spontaneously by the time of the examination and a third lesion, although persisting, became significantly smaller after delivery with typical features of a deep nodule without blood flow. Highly vascularised pelvic findings that may mimic malignancy were observed in 33% of the women. After delivery the findings had resolved or appeared as typical endometriosis nodules, suggesting that the sonographic changes were hormone-dependent, possibly due to decidualisation. Supporting information for OC01.03, OC01.04, OC01.07, OC01.08, OC02.02, OC02.10, OC04.05, OC05.07, OC05.10, OC06.03, OC07.03, OC07.04, OC07.10, OC08.04, OC10.06, OC10.09, OC10.11, OC11.01, OC11.03, OC11.04, OC11.08, OC13.05, OC13.06, OC13.08, OC13.10, OC14.02, OC14.03, OC14.04, OC14.08, OC14.10, OC15.06, OC17.02, OC18.10, OC19.02 can be found in the online version of these abstracts.