Pulsations of the ductus venosus blood velocity and diameter are more pronounced at the outlet than at the inlet

Objective: To test the hypothesis that the pulse wave emitted from the heart into the precordial veins is altered as it travels towards the periphery. Study design: Ultrasound diameter measurement and Doppler recording at the inlet and outlet of the fetal ductus venosus in 20 normal pregnancies (gestational age 19-41 weeks) were used to compare velocity patterns and diameters applying paired t-test and Spearman's rank correlation. Results: There was a significantly lower pulsatility of the blood velocity in the ductus venosus at the inlet compared to the outlet, and, correspondingly, there was a significantly smaller diameter pulsation at the inlet than at the outlet. Conclusion: Both blood velocity and diameter pulsations are smaller at the inlet than at the outlet of the ductus venosus. The tapering shape of the vessel and the diameter differences at the junction with the umbilical vein are suggested to be important factors affecting the velocity waveform. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.