How to record ductus venosus blood velocity in the second half of pregnancy

The ductus venosus (DV) is a shunt between the intra-abdominal umbilical vein and inferior vena cava (IVC) that directs well-oxygenated blood preferentially through the foramen ovale into the left heart, thus feeding the coronary and cerebral circulation. The shunt is thin, slightly funnel-shaped, straight or with variable curvature, and ascends towards the IVC at an angle of roughly 50°. The isthmus at its inlet has a regulatory function, but is also responsible for the characteristic high blood velocity and is the standard site of recording. The high velocity ensures high kinetic energy needed for preferential streaming, but also reflects the pressure gradient that drives venous liver perfusion. The pressure gradient between IVC and umbilical vein varies with the phase of the heart cycle, resulting in changes in DV blood velocity. The blood flow velocity waveform, particularly the deflection during atrial contraction (a-wave), is commonly used in hemodynamic evaluation of the fetus, for example in fetal growth restriction. Doppler recording requires some training and patience to reach a reliable level of skill.

This 'How To' article and accompanying slides provide practical advice on the recording of blood flow velocity within the fetal ductus venosus in the second half of pregnancy.

Read the full article and download the slide presentation of step-by-step guidance below