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 hear t 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 (ges tational age 19-41 weeks) were used to compare velocity patterns and diamet ers applying paired t-test and Spearman's rank correlation. Results: There was a significantly lower pulsatility of the blood velocity in the ductus v enosus 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 th e 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 vei n are suggested to be important factors affecting the velocity waveform. (C ) 1999 Elsevier Science Ireland Ltd. All rights reserved.