To assess the best method of combining fetal nuchal translucency (NT) and ductus venosus (DV) blood flow measurements in the detection of major cardiac defects in chromosomally normal fetuses during the first-trimester scan.Methods
During an 8-year period NT and DV blood flow were routinely assessed at 11–14 weeks' gestation. Only chromosomally normal singleton pregnancies were included in the study. When a cardiac defect was suspected, or when increased fetal NT and/or absent or reversed (AR) A-wave in the DV was observed, early fetal echocardiography was offered. Data on routine second- and third-trimester scans, neonatal follow-up or postmortem examination were obtained from hospital records. The detection and false-positive rates for all major cardiac defects were calculated for several screening strategies, including: NT or DV pulsatility index for veins (DV-PIV) above a fixed normal centile; AR A-wave; risk based on NT and DV-PIV or A-wave velocity above a fixed normal centile; and combinations of these strategies.Results
The study population included 37 chromosomally normal fetuses with a major cardiac defect and 12 799 unaffected pregnancies. Fetal NT above the 95th or the 99th centile and AR A-wave was observed in 40, 27 and 39% of the fetuses with major cardiac defects, respectively. A 47% detection rate with a 2.7% false-positive rate was obtained when AR A-wave or NT above the 99th centile was used as the selection criterion.Conclusions
Half of major fetal cardiac defects could be detected in the first trimester if NT and DV Doppler are used to select 2.7% of the general pregnant population for extended fetal echocardiography. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.