Prenatal evaluation and postnatal outcomes of fetal ovarian cysts.

To evaluate the natural history and outcome of cases of fetal ovarian cyst under conservative prenatal treatment. A retrospective cohort study included patients diagnosed with fetal ovarian cysts was conducted between January 2008 to December 2016. Data including clinical data, sonographic feature and postnatal outcomes were obtained. One hundred and two cases were included for statistical analysis. The rate of spontaneous resolution was significantly higher among cases with simple than complex cysts (70/92 or 76.1% vs 2/10 or 20%, P < .01) and for cysts <4 cm than cysts ≥4 cm (50/56 or 89.3% vs 22/46 or 47.8%, P < .01). Ovarian torsion was confirmed in 5/102 (4.9%) cases; neither prenatal characteristics of cysts (complex: 2/10 or 20% vs simple: 3/92 or 3.3%, P = .07), nor their size (≥40 mm: 4/46 or 8.7% vs < 40 mm: 1/56 or 1.8%, P = .17) was predictive for ovarian torsion. 25/102 (24.5%) of cysts change in size or sonographic characteristics prenatally. Half of the complex cysts at the last prenatal scan are not ovarian in origin. 98/102 neonates (96.1%) were able to preserve both ovaries. Spontaneous resolution of ovarian cysts is predicted by cyst size and characteristics, whereas likelihood of torsion cannot be predicted.