Fetal ovarian cysts are common prenatal findings with a highly variable clinical course, ranging from spontaneous resolution to complications such as torsion, hemorrhage, or rupture requiring surgery. Current prenatal classification is mainly based on the distinction between "simple" and "complex" cysts; however, this approach may be insufficient to accurately predict outcomes and guide perinatal management.

This multicenter prospective observational study aims to validate a management model based on the International Ovarian Tumor Analysis (IOTA) terminology for ultrasound characterization of fetal ovarian cysts. Pregnant women carrying a fetus with an ovarian cyst will be enrolled and followed with serial ultrasound examinations during pregnancy and after birth. Cysts will be classified according to morphology and cyst content (anechoic, low-level, ground-glass, hemorrhagic, mixed, and others) and managed according to a predefined protocol based on cyst size and ultrasound features.

The primary objective is to assess the rate of complications requiring postnatal surgery in conservatively managed fetal ovarian cysts with anechoic or low-level cystic content smaller than 4 cm. Secondary objectives include evaluation of complication rates in larger cysts managed with aspiration procedures, rates of spontaneous cyst resolution, rates of ovarian torsion, and the presence of normal ovarian parenchyma at histology in surgically treated cases.

The study aims to improve prenatal risk stratification and optimize perinatal management in order to reduce unnecessary surgery and preserve ovarian function.

Inclusion Criteria:

Pregnant women aged ≥18 years Singleton or multiple pregnancies with fetal ovarian cyst diagnosed by prenatal ultrasound at any gestational age Signed informed consent

Exclusion Criteria:

Refusal to provide informed consent

Pregnant women with a prenatal ultrasound diagnosis of fetal ovarian cyst, recruited consecutively across participating centers, and followed prospectively from diagnosis until postnatal follow-up according to a standardized management protocol based on IOTA ultrasound classification.