Should second trimester ultrasound be routine for all pregnancies

Ultrasound use has become ubiquitous in pregnancy. We review the evidence regarding the benefits of routine ultrasound use during pregnancy. Routine ultrasound use before 24 weeks improves detection of undiagnosed twins, reduces postdates inductions, and allows detection of fetal anomalies before birth. Wide variations exist in the sensitivity of ultrasound in detecting fetal anomalies. These may be related to equipment, training, and maternal characteristics, such as obesity. Standards have been developed for the performance of routine fetal ultrasonography in the second trimester. The benefits of routine first trimester ultrasound in the diagnosis of structural fetal anomalies or of routine ultrasonography after 24 weeks are not proven. As ultrasound technology improves and obstetrical care changes, new uses of routine ultrasonography may emerge.