Umbilical venous Doppler waveform without fetal breathing: its significance

Umbilical venous waveforms by Doppler ultrasound are seen normally during fetal breathing movements. Each waveform extends two to four fetal cardiac cycles. During Doppler study of gross intrauterine growth retardation (IUGR) and twin to twin transfusion cases, single or double peaked umbilical venous waveforms were detected with each fetal cardiac cycle. Umbilical arterial Doppler study detected minimal, absent, or reverse diastolic flow. In these fetuses, the ratio of right and left ventricular diameters at the atrioventricular valve level was increased, and pulse-wave and color Doppler study showed tricuspid regurgitation. This tricuspid regurgitation caused reverse flow in the umbilical vein from the right atrium and inferior vena cava and produced characteristic venous waveforms. These umbilical waveforms were associated with gross IUGR or cardiac failure of the fetuses with perinatal morbidity and mortality.