Nearly half of all severe fetal anomalies can be detected by first-trimester screening in experts' hands

Abstract

Objective To evaluate the detection rate of severe fetal anomalies at the first-trimester screening (FTS) and, vice versa, to evaluate the follow-up of pathological results at FTS at the time of mid-trimester screening (MTS) and throughout pregnancy and delivery in a partially selected population of low-risk pregnancies. Methods We conducted a prospective study on the detection of severe fetal anomalies at routine FTS in 9891 pregnant women with 10,294 fetuses between 11 + 0 and 13 + 6 weeks of gestation. The findings of FTS were compared to the results of MTS and pregnancy and neonatal outcomes. Only cases with severe fetal anomalies were taken for statistical analysis in this study. Results There were 232 cases of fetal anomaly altogether. At the time of FTS, sonographic anomalies were diagnosed in 113 cases and further ultrasound controls arranged. In four cases, fetal anomaly was not confirmed by MTS; in the remaining 109 cases, the sonographic anomaly seen at FTS was confirmed at MTS and in the course of pregnancy with a resulting sensitivity for fetal malformation at FTS of 47.8%, a specificity of 99.96%, a positive predictive value of 96.5% and a negative predictive value of 98.8%. Conclusion FTS can detect almost half of all severe fetal anomalies at an early stage of pregnancy with positive predictive values of 90% and more. Sensitivities varied depending on the organ system and reached the highest figures for anomalies of the heart, the abdomen, the spine and the skeletal system.

Keywords: antenatal care; fetal anomalies; first-trimester screening; pregnancy screening; ultrasound.