OC03.06: Validation of ADNEX and the IOTA two‐step strategy and estimation of risk of complications during follow‐up of adnexal masses in a low‐risk population

findings in pre-and postpubertal CAYAs differ from adults and diagnostic models are not validated.We aim to assess the incidence and management of ovarian pathology in this cohort.Methods: Retrospective review of pelvic USS performed in CAYAs < 18 years of age from January 2017 to July 2021.Statistical analysis was computed in R (V4.1.2) on 3 age groups: neonatal (< 1 year), premenarchal (> 1 year), and postmenarchal.Results: In total, 1429 USS were retrieved, 116 were excluded (duplicate data, non-gynecological imaging), and 1313 USS (1198 patients) were reviewed.Median age in each group was 2 days (neonatal), 8.8 years (premenarchal) and 16.1 years (postmenarchal).TA USS was performed in all neonates (n = 20), premenarchal (n = 124) and 93% of postmenarchal CAYAs (n = 894).Adnexal pathology was identified in 108 participants: 4 neonates (20.3%), 3 premenarchal (2.4%) and 93 postmenarchal CAYAs (10.3%).Median number of scans was 2 per CAYA (1-6).Median maximum cyst diameter was 37.8 mm, 19.0 mm and 43.1 mm.Benign cystadenomas were most common in neonates (n = 2, 50.0%) and postmenarchal CAYAs (n = 39, 38.6%), then hemorrhagic cysts (n = 33, 32.7%).Ninety-two masses were classified as benign using IOTA Simple Rules (specificity 90.1%).There were no malignancies.Sixty CAYAs had serial scans for cyst surveillance: 48 (80.0%) resolved expectantly, 5 persisted (8.3%) and 7 required surgery (11.7%).Twelve patients required surgery overall (3 oophorectomies, 6 cystectomies and 3 cyst aspirations), 11/12 were classified as benign retrospectively.Histology was available for 6 masses, which were all benign.Conclusions: USS is effective for assessing the female pelvis in CAYAs.Adnexal masses are common, but few require surgical intervention.Larger studies are required for the prospective validation of diagnostic models, which may aid a fertility-sparing approach to care.