Non-invasive screening for chromosomal abnormalities, such as Down’s Syndrome, could become more accurate if an assessment of the blood flow of the ductus venosus (the vascular channel between the umbilical cord and the fetus’ heart) is carried out in combination with nuchal translucency, according to research published in the BJOG (British Journal of Obstetrics and Gynaecology) today.
Researchers from St George’s Hospital Medical School, London, examined 256 pregnancies between 11-14 weeks of gestation referred to the tertiary fetal medicine unit over an 18-month period. Nuchal translucency was measured and colour Doppler imaging was used to assess normal or abnormal ductus venosus flow during atrial contraction.
The study confirmed a clear association between abnormal blood flow in the ductus venosus and fetal aneuploidy (chromosomal abnormalities), as shown by earlier studies. Abnormal ductus venosus flow increases the risk for fetal aneuploidy by 10-fold.
The researchers found the sensitivity in the detection of Down’s Syndrome increased to 93.5% when ductus venosus velocimetry was carried out in combination nuchal translucency. This compared to 80.4% for nuchal translucency alone and 58.7% for ductus venosus velocimetry alone.
Dr Basky Thilaganathan and colleagues however warn: “The specialised nature of Doppler velocimetry of the ductus venosus performed in the first trimester may hinder the widespread acceptance of this test in screening.”