Improving our Knowledge in Twins: The Role of Ductus Venosus in the First Trimester

Ductus venosus (DV) is a tiny vessel with a central role in fetal circulation both in singletons and multiples. In the present review we detail the contribution of DV evaluation in twin pregnancies in the first trimeter of pregnancy. The higher prevalence of abnormal A-wave in fetuses with abnormal karyotype and/or cardiac defects made DV evaluation a useful marker for the screening of chromosomal abnormalities and fetal cardiac anomalies. In dichorionic (DC) pregnancies, DV blood flow assessment reproduces the role of NT in the screening for aneuploidies, just as in singleton pregnancies. In monochorionic (MC) twin pregnancies, the Doppler assessment of DV blood flow improves the detection of those at higher risk of developing twin-to-twin transfusion syndrome or growth discrepancy later in pregnancy. As for singletons, DV should be systematically evaluated in all first trimester scans for a more performant screening in multiples.