F120Effectiveness of screening for major cardiac defects in a routine obstetric population

Background The aim of this study is to evaluate the effectiveness of routine antenatal screening for CHD in a routine obstetric population. Method A three-year prospective, observational study. All women were routinely offered first trimester nuchal translucency screening and an 18–23 week anomaly scan, where the four chamber view and outflow tracts were visualised. The main outcome measure was identification of major CHD in all pregnancies, either in the antenatal or postnatal period. Results Major defects of the heart and the great arteries were identified in 51 out of 9277 pregnancies. Major CHD were diagnosed antenatally in 42 fetuses and postnatally in nine (including 15 aneuploidies). The overall antenatal detection rate was 82.4% in all pregnancies and 80.6% in chromosomally normal pregnancies. In 10 cases, the first trimester NT measurement was increased. Conclusion The overall prevalence of major CHD (5.4/1000) suggests that ascertainment in the study population was thorough. The combination of first trimester NT screening and visualisation of the four-chamber/outflow tracts is effective in the detection of the majority of major CHD.