The role of ductus venosus Doppler flow in the diagnosis of chromosomal abnormalities during the first trimester of pregnancy.

Background: The ductus venosus (DV) is an intrahepatic end-part of the umbilical vein. Inappropriate first trimester DV Doppler blood flow patterns correspond to a higher risk of chromosomal abnormalities.
Objectives: The aim of the study was to assess the usefulness of ductus venosus Doppler flow in a first trimester screening for aneuploidies.
Material and Methods: A prospective study included 1526 singleton pregnancies with increased risk of chromosomal abnormalities who underwent prenatal first trimester screening between the years 2006-2009. All ultrasound scans were performed by experienced sonographers and included an assessment of fetal growth, nuchal translucency (NT), nasal bone assessment (NB) and ductus venosus (DV) blood flow. Reversed a-wave (atrial diastole) in the ductus venosus flow pattern was recognized as abnormal. In addition to DV blood flow, the levels of pregnancy-associated plasma protein-A (PAPP-A) and free β - human chorionic gonadotropin (β-hCG) in maternal serum were measured. The risk of chromosomal abnormalities was calculated using the Fetal Medicine Foundation software. The following risk levels were assumed: high risk results - 1:100 or lower, intermediate risk 1:100 - 1:1000, and low risk above 1:1000. In 523 pregnancies, patients underwent amniocentesis and karyotyping.
Results: The authors diagnosed 46 cases with chromosomal abnormalities (using amniocentesis and karyotyping). 29 patients had spontaneous miscarriage, in 21 cases they reported fetuses with congenital malformations (mostly heart defects). Abnormal DV blood flow was recognized in 113 pregnant women (7.4%). The majority of cases affected by abnormal DV blood flow were classified as intermediate and high disorder risk groups - 100 (6.5%). The comparison between a combined test with and without DV assessment revealed that the addition of DV flow pattern results increased sensitivity from 84% to 92% in screening for aneuploidies. The false-positive ratio was between 0.4% and 2.4%.
Conclusions: Ductus venosus Doppler blood flow examination is useful in the first trimester prenatal diagnostic since it increases the sensitivity of the combined test in the assessment of risk for chromosomal abnormalities. The authors recommend assessing DV blood flow during the first trimester screening in all pregnancies, irrespectively of the chromosomal abnormalities background risk. This procedure in clinical practice seems to be favorable and less complicated.