"use a small Doppler sample volume (0.5–1 mm) to avoid contamination from the inferior vena cava or hepatic veins⁷"
"use a high sweep speed (2–3 cm/s) to spread the waveform and allow clear assessment of the A‑wave⁸"
"monochorionic complications (e.g. TTTS, TAPS)"
"monochorionic complications (e.g. TTTS, TAPS)"
"Of the precardiac veins, the ductus venosus provides the most accurate assessment of fetal cardiac function and myocardial haemodynamics⁴."
"Radiographic features"
"Ultrasound"
"Technique"
"obtain a right ventral mid‑sagittal view of the fetal trunk⁵"
"use colour Doppler to demonstrate the umbilical vein, ductus venosus and fetal heart"
"sampling should be performed where the umbilical vein joins the ductus venosus (DV isthmus)⁶"
"the probe may be angled to obtain a mid‑sagittal or transverse oblique plane through the fetal abdomen"
"the probe may be angled to obtain a mid‑sagittal or transverse oblique plane through the fetal abdomen"
"use a small Doppler sample volume (0.5–1 mm) to avoid contamination from the inferior vena cava or hepatic veins⁷"
"maintain an insonation angle ≤30°"
"use a high sweep speed (2–3 cm/s) to spread the waveform and allow clear assessment of the A‑wave⁸"
"set the wall filter low so the A‑wave is not obscured⁸"
"Doppler waveform"
"The ductus venosus demonstrates a triphasic waveform with forward flow throughout the cardiac cycle⁹."
"The ductus venosus demonstrates a triphasic waveform with forward flow throughout the cardiac cycle⁹."
"lowest point of the waveform but normally remains above the baseline (forward flow)"
"Reversal of the A‑wave (i.e. crossing the baseline) is always abnormal¹⁰."
"S‑wave"
"A‑wave"
Expected headings
"Radiographic features"
"Ultrasound"
"Technique"
"Doppler waveform"
"hydrops, arrhythmia or high‑output states"
"monochorionic complications (e.g. TTTS, TAPS)"
"variability in the heights of the S and D waves may indicate fetal breathing, which is normal; wait for fetal quiescence before evaluating"