Fetal structural anomalies diagnosed during the first, second and third trimesters of pregnancy using ultrasonography: a retrospective cohort study.

Ultrasound is safe and has utility for detecting fetal anomalies that are associated with high rates of morbidity and mortality. However, the low sensitivity of ultrasound for detecting fetal anomalies in unselected populations limits its utility for providing reassurance to examiners and to pregnant women with normal results.