Reproducibility and inter‐observer variability of intra‐ and extra‐abdominal umbilical venous flow velocity and left portal venous flow velocity as well as heart‐synchronous waveform pulsations in these vessels were studied in 23 women at 34–38 weeks of normal pregnancy. Limited reproducibility, expressed by large intra‐patient coefficients and limits of agreement between two observers, was established for all standardized recording sites. Pulsations, defined as negative venous deflections of at least 10% of the mean velocity, were demonstrated at all locations ranging from 19.6% of the measurements at the free‐floating loop of the umbilical vein to 78.4% of the measurements at the left portal vein. The present study shows that the limited reproducibility of venous flow velocity waveforms should be taken into consideration, and that the presence of pulsations can be demonstrated in normal late pregnancy. Copyright

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Ultrasound in Obstetrics and Gynecology
Department of Gynaecology & Obstetrics

van Splunder, I., Huisman, T., Stijnen, T., & Wladimiroff, J. (1994). Presence of pulsations and reproducibility of waveform recording in the umbilical and left portal vein in normal pregnancies. Ultrasound in Obstetrics and Gynecology, 4(1), 49–53. doi:10.1046/j.1469-0705.1994.04010049.x