Venous Doppler studies in low-output and high-output hydrops fetalis

The objective of the study was to compare fetal venous Doppler flow reflecting cardiac function in fetuses with hydrops fetalis between a group of congenital heart defect (low cardiac output) and a fetal anemia group (high cardiac output).

This was a prospective cross-sectional analysis. It was conducted at the Maharaj Nakorn Chiang Mai Hospital, Tertiary center, Medical School. The study included fetuses with hydrops fetalis secondary to cardiac causes (low output group) and anemia (high output group). All fetuses underwent ultrasound examination to assess ductus venosus (DV) and umbilical vein (UV) Doppler indices. The results were related to normal reference range and were also compared between the group of high-output and the low-output group.

Sixty-nine hydropic fetuses were available for analysis, 50 in the high-output group and 19 in the low-output group. The peak velocity index, preload index, and the pulsatility index of the DV were significantly low in the high-output group, whereas they were significantly high in the low-output group. The umbilical vein pulsations were found in 78.9% of the fetuses with low-output hydrops fetalis but only 28.0% of fetuses in the high output group (P < .001).

New insights gained from this study are that hydrops caused by severe anemia because of hemoglobin Bart's is not associated with high central venous pressures as is seen in hydropic fetuses with coronary heart disease. This suggests that cardiac decompensation is not the primary mechanism of hydrops in these anemic fetuses. Additionally, umbilical vein pulsations are not a sign of cardiac failure in the anemic group.