Comparison between color Doppler cineloop‐ and conventional spectral Doppler‐derived maximum velocity and flow in the umbilical vein

Abstract

Objective

Umbilical venous blood flow measurement: accuracy and reproducibility

“…It clearly shows that there is a trend to find higher values of flow when mean velocities are estimated from the IWMV compared with from the mean and maximal velocity20, 23, 25, 26, 37. Accordingly, Gerada et al 29, summarizing the findings of 20 published studies on umbilical venous flow, also reported that studies in which mean velocities were estimated from the IWMV show higher blood flow values at 30 weeks. However, estimating the mean velocity from Vmax cannot be considered error‐free either.…”

“…The umbilical vein is the longest venous vessel in the human fetus and it has been demonstrated in vivo that, at its free‐floating portion, its diameter decreases progressively from the fetus to the placenta13. Both intra‐abdominal1, 4, 10, 14–24 and free‐floating21, 25–29 portions of the umbilical vein have been used to estimate vessel area. When a free‐floating portion of the umbilical vein is used, the area is calculated directly26, 28, 29 or from the vessel diameter21, 25, 27 (CSA = π × (diameter/2) 2 ).…”

“…Both intra‐abdominal1, 4, 10, 14–24 and free‐floating21, 25–29 portions of the umbilical vein have been used to estimate vessel area. When a free‐floating portion of the umbilical vein is used, the area is calculated directly26, 28, 29 or from the vessel diameter21, 25, 27 (CSA = π × (diameter/2) 2 ). Not surprisingly, normal ultrasound values differ beyond the expected biological variability according to the technique used for estimation: at 30 weeks the mean venous cross‐sectional area is 22.6 mm 2 at the intra‐abdominal portion24, while at the free‐floating portion it is 32.2 mm 2 using diameter calculation27 and 40 mm 2 using direct area calculation28.…”

Transabdominal Insonation of Fetal Basilar Artery: A Feasibility Study

“…The diameter of fetal basilar artery is smaller than the diameter of middle cerebral artery and only a small segment of basilar artery is visualized for waveform acquisition. Since estimates of velocity are derived from the phase shifts or time delays between echoes from the same sample volume during subsequent pulses, the smaller sampling area of the cross‐sectional vessel may result in lower values for flow velocities . The axis of the basilar artery in sagittal view is less favorable than axis of the middle cerebral artery in axial view.…”

“…The axis of the basilar artery in sagittal view is less favorable than axis of the middle cerebral artery in axial view. Therefore, manual positioning of probe is technically more difficult to achieve insonation angles of less than 30° . The internal carotid artery and internal jugular vein can be seen in the same plane and require differentiation using anatomical landmarks and waveform analysis.…”