(1) Background: adnexal masses during pregnancy detection are increased due to the use of first trimester screening and to advanced maternal age. Although the low risk of malignancy, other risks are associated: torsion, rupture or labour obstruction. Correct diagnosis and management are fundamental to guarantee both maternal and fetal safety. Adnexal masses may be troublesome to classify during pregnancy due to the increase in the uterus volume and to pregnancy-related hormonal changes. Management should be based on ultrasound examination to provide the best treatment. (2) Methods: the aim was to describe the ultrasound features of ovarian masses detected during pregnancy. We evaluated patient’s management, perinatal outcomes and follow-up. (3) Results: our study demonstrated that the management should be guided by an accurate ultrasound examination performed by an expert operator according to standardized techniques. Secondly, our results confirm the data present in the literature: the masses are most frequently benign, ultrasound follow-up is the best management strategy and obstetric outcome is not considerably affected. (4) Conclusions: the management of patients with ovarian masses detected during pregnancy should be based on ultrasound examination and a centralization in referral centers for ovarian masses should be considered.