The role of ductus venosus blood flow assessment in screening for chromosomal abnormalities at 10-16 weeks of gestation

Objective To evaluate the role of ductus venosus blood flow assessment at 1 0-16 weeks' gestation in screening for chromosomal abnormalities. Methods Ductus venosus blood flow runs prospectively evaluated in 1371 cons ecutive pregnancies between 10 and 16 weeks of gestation. The pulsatility i ndex for veins was calculated. All cases were screened for chromosomal defe cts combining maternal age and fetal nuchal translucency thickness. Results A chromosomal abnormality was found in 20 cases. The overall detect ion rate, specificity, positive predictive value, negative predictive value and odds ratio for chromosomal abnormalities were 65%, 95.7%, 18.3%, 99.5% and 41 (95% CI 16-108), respectively, when using the 95th centile pulsatil ity index us a cut-off. Conclusions These preliminary results suggest that evaluation of the ductus venosus pulsatility index at 10-16 weeks' gestation is a useful second-lin e screening test for chromosomal defects. A combination of nuchal transluce ncy measurement and ductus venosus assessment might increase specificity wh ile maintaining an optimal detection rate for chromosomal abnormalities. Su ch a policy could identify 55% of all chromosomal abnormalities and about 6 9% of autosomal trisomies, reducing the need for invasive testing to less t han 1%.