Ultrasonographic diagnosis of fetal structural abnormalities in prenatal screening at 11-14 weeks.

PURPOSE The aim of the study was to determine the detection rate of structural abnormalities at the 11-14 week ultrasound examination as a part of two-stage screening process in low-risk pregnancies. MATERIALS AND METHODS A total of 1085 consecutive low-risk pregnant women participated in screening by two-stage ultrasonography for the estimation of the sensitivity of the first and second trimester ultrasound scans in the detection of major anomalies as a part of routine screening. RESULTS Of 1085 pregnancies, 21 (1.93%) fetuses had at least one major structural defect considered detectable by routine ultrasound screening; 14 (1.29%) were identified at early screening and an additional 5 (0.47%) at late screening. Two abnormalities were not detected prenatally, and data were obtained from the patients after delivery. CONCLUSION The majority of fetal structural abnormalities can be detected by sonographic screening at 11-14 weeks, but detailed fetal anatomic survey performed at 18-22 weeks should not be abandoned.