First trimester screening for major cardiac defects based on the ductus venosus flow in fetuses with trisomy 21.

OBJECTIVE: To examine whether in fetuses with trisomy 21 (T21), the ductus venosus (DV) flow differs in presence of a major cardiac defect (congenital cardiac defect [CHD]) and whether this affects the risk distribution in first trimester screening for T21.

METHODS: This retrospective study included pregnant women who underwent first trimester screening. This involves an examination of the crown-rump length, the nuchal translucency, the ductus venosus (DV) flow, and the heart. Three groups of fetuses were examined: euploid without CHD, T21 with CHD, and T21 without CHD. We examined the DV pulsatility index for veins, the direction of the a-wave, and ratios of velocities: v/S, v/D, a/S, a/D, and S/D.

RESULTS: The study population consisted of 410 euploid fetuses and 136 with T21 (51 with CHD and 85 without CHD). In the 3 groups, the a-wave was reversed in 3.2%, 66.7%, and 57.6%. The DV flow ratios in T21 with and without CDH were significantly different compared with normal fetuses. When comparing the ratios between the 2 T21 groups, only the a/S and a/D ratio were significantly different. The risk distributions in screening for T21 with and without CDH were similar.

CONCLUSION: There are some small differences in the DV flow of T21 fetuses with and without CHD, but they are not clinically useful.