Using IOTA terminology to evaluate fetal ovarian cysts: analysis of 51 cysts over 10-year period

ObjectivesTo describe ultrasound features of fetal ovarian cysts as reported by the original ultrasound examiner, to apply International Ovarian Tumor Analysis (IOTA) terminology after retrospective analysis of the images and to describe patient management and evolution of fetal cysts during pregnancy and after delivery. MethodsThis retrospective observational study included pregnant women diagnosed on ultrasound examination with a fetal ovarian cyst at the Prenatal Diagnosis Division of the Bambino Gesu Children's Hospital, in Rome, between March 2011 and May 2020. Cysts were classified by the original ultrasound examiner as 'simple' (unilocular anechoic cyst) or 'complex' (cyst with other morphology). In addition, three ultrasound examiners, experienced in gynecologic ultrasound, classified retrospectively the fetal ovarian cysts according to IOTA terminology, by reviewing stored ultrasound images. The evolution of these fetal ovarian cysts during pregnancy and after birth was recorded. ResultsIncluded were 51 ovarian cysts in 48 fetuses. Of the 51 cysts, 29 (56.9%) had been classified by the original ultrasound examiner as 'simple', and 22 (43.1%) as 'complex'. Of the simple cysts, the majority (20/29 (69.0%)) resolved spontaneously after delivery, 2/29 (6.9%) resolved following intrauterine aspiration, 2/29 (6.9%) resolved after postnatal aspiration and 5/29 (17.2%) underwent surgery due to persistence after delivery; in all five, normal ovarian parenchyma without signs of necrosis was observed at histology. Of the complex cysts, 7/22 (31.8%) resolved spontaneously. The other 15/22 (68.2%) were removed surgically and, at histology, necrosis was observed in most (12/15 (80.0%)), while a benign epithelial cyst with normal ovarian parenchyma was observed in 3/15 (20%). After reviewing the ultrasound images and applying IOTA terminology, all 51 (100%) fetal cysts were described as unilocular; 29/51 (56.9%) cysts showed anechoic content (described as simple cysts by