The last 2 decades have seen considerable advances in obstetric ultrasonography, which now forms part of routine prenatal care in most countries. Congenital anomalies often occur sporadically and unpredictably. The prenatal identification of an abnormal fetus allows the opportunity for prenatal counseling with a multidisciplinary team of experts, and a thorough discussion of pregnancy options. Furthermore, prenatal diagnosis can influence antepartum and intrapartum management, and permit the planning of the mode and site of delivery, thus ensuring optimal care of the fetus and the newborn. Prenatal surgical therapy can also be offered to fetuses with simple anatomic defects that have predictably devastating developmental consequences. This review discusses controversies regarding the accuracy, limitations and the roles of ultrasound in pregnancy.