THE ACCURACY OF PRENATAL ULTRASONOGRAPHY IN DETECTING CONGENITAL-ANOMALIES

OBJECTIVES: The purpose of this study was to evaluate the accuracy of prenatal ultrasonography in detecting congenital anomalies. STUDY DESIGN: We studied all singleton births or fetal deaths with one or more congenital defects delivered during the study period who had had one or more ultrasonographic examinations performed at or after 16 weeks' gestation and a random sample of defect-free newborns similarly examined by ultrasonography. Congenital anomalies reported on either the infants' postdelivery medical record or the fetal autopsy report were our standard. Prenatal ultrasonographic findings reported during gestation and therefore ''blind'' to the postdelivery outcome were then compared with the standard. RESULTS: The overall sensitivity of ultrasonography in detecting defects was 53%. The overall specificity was 99%. Ultrasonography proved to be highly sensitive (89%) for prevalent lethal malformations. However, serious cardiac defects, microcephalus, and many musculoskeletal deformities were missed by ultrasonography. CONCLUSION: Ultrasonography is sensitive in detecting many lethal malformations. However, a negative prenatal ultrasonographic examination does not provide absolute assurance that a fetus is defect free.