A randomized trial of prenatal ultrasonographic screening: Impact on maternal management and outcome

OBJECTIVES: This randomized clinical trial of 15,530 women was designed to test the hypothesis that screening ultrasonography in low-risk pregnancies would improve perinatal outcome. A secondary hypothesis addressed in this article was that screening ultrasonography would have a favorable impact on maternal management or outcome. STUDY DESIGN: Pregnant women without a specific indication for ultrasonographic examination in early pregnancy were randomly assigned to have either two screening sonograms or conventional obstetric care. Pregnancy interventions and maternal outcomes were compared in the two groups. RESULTS: No significant differences were found in maternal outcomes. Use of ultrasonography was markedly higher in the screened group. The rates of induced abortion, amniocentesis, tests of fetal well-being, external version, induction, and cesarean section and the distribution of total hospital days were similar in the two groups. Use of tocolytics and the rate of postdate pregnancy were both slightly lower in the screened group. CONCLUSION: Screening ultrasonography resulted in no clinically significant benefit.