P-757 The classification and management of adnexal masses identified during pregnancy

Abstract Study question How do we classify adnexal masses (ovarian cysts) identified during pregnancy and how should manage them? Summary answer Adnexal be managed expectantly in pregnancy, given the low rate of complications prevalence malignancy. What is known already Conservative management preferable due to maternal fetal risks associated with surgery. Accurate diagnosis key safe expectant management. Various ultrasound-based models exist masses; however, none have been validated for use pregnancy. mass morphology can change decidualisation, which often difficult distinguish from underlying neoplastic processes. We aim evaluate:(1) performance current methods classification (2) understand natural course particularly presence decidualisation incidence complications. design, size, duration Retrospective analysis prospectively collected data between January 2017- November 2022. To cysts), evaluated: Expert subjective assessment (SA), IOTA Simple Rules (SR) Assessment Different Neoplasias Adnexa (ADNEX) model. The end point was either histological examination tissue removed at surgery or postnatal scan women conservatively. Participants/materials, setting, Women an on gynaecological ultrasound a tertiary London University Hospital were included. Relevant clinical extracted, including age, gestation cyst-related classified first antenatal according SA, SR ADNEX model (10% risk malignancy cut off) correlated histology surgically. simple descriptors used benign masses. Main results role chance 254 (median age 33-years old, range:18-49) mass/cyst included median 12 weeks, (range:4-36). 13 (5.1%) conceived through assisted reproductive techniques. Spontaneous resolution occurred 24.5% cases, 21 lost follow up (8.3%). According Descriptors, 38.6% simple, 22.0% endometriomas 19.7% dermoid cysts. Antenatally, SA outperformed ADNEX, based specificity (94.6 vs.92.2%) sensitivity (60 vs.55.6%) respectively. had negative predictive value(NPV) 96.1% 98.3% Postnatally, higher than (75 vs.50%), but lower (94.1 vs.96.9%). NPV 94.1% 97.5% Three (1.3%) underwent acute pregnancy: one ovarian torsion (9/40), two cyst ruptures (11/40, 30/40). Presumed 29.5% endometriomas. removal caesarean section, suspicion BOTs (one suspected decidualisation) patient preference. On histology, decidualised serous BOT, BOT struma ovarii. In period (12 weeks), four BOTs, confirmed cystadenomas histology. Limitations, reasons caution dataset as expected contains relatively small number malignancies (prevalence 3.9%) so any test discriminate malignant disease must interpreted caution. A larger prospective multicentre study needed this. Wider implications findings Our suggest that cysts will resolve, few very low. Accordingly, supports approach detected Trial registration Not applicable