It is often difficult to spot the ductus venosus among the numerous vessels in the fetal abdomen. I have devised an easy way out.
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a) First spot the umbilical vein passing through the fetal abdomen.
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b) Switch on the color Doppler function to view the flow of the umbilical vein.
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c) Reduce or increase the PRF (pulse repetition frequency) function of the color flow until you spot a prominent but short vessel with MARKED ALIASING (ie: turbulent flow producing a multiple shades in the flow image). This is most likely to be the ductus venosus. Note the location of the vessel, just anterior to the fetal aorta.
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d) Now switch on the spectral doppler trace of the vessel. This will give a wavy spectral waveform with 3 waves (d): The S wave, the D wave and the A wave. Note the marked diastolic flow in this waveform. This is diagnostic of a normal Ductus venosus. All images by Joe Antony, MD, using a Toshiba Nemio -XG ultrasound system.
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