J Kessler1, S Rasmussen, T Kiserud. 1. Department of Clinical Medicine, Section for Obstetrics and Gynecology, University of Bergen, University of Bergen and the Norwegian Institute of Public Health, Bergen, Norway.
Abstract
OBJECTIVES: The left portal vein represents a watershed area in the fetal circulation and the change of flow direction is a suggested marker of circulatory compromise. Our aim was to study the left portal vein of uncompromised human pregnancies and establish reference ranges. METHODS: One hundred and sixty low-risk pregnant women were recruited to a longitudinal study that included four to five Doppler measurements at monthly intervals during the second half of pregnancy. RESULTS: Based on 554 Doppler recordings we found time-averaged maximum flow velocities increasing from a mean of 10.6 cm/s to 14.2 cm/s during 21-31 weeks of gestation, remaining stable until 37 weeks and decreasing towards term. Intermittent flow reversal occurred during fetal respiratory movements, and continuous flow reversal was seen in 2/160 fetuses close to delivery. CONCLUSIONS: We propose time-averaged maximum blood velocity measurement for quantification of the watershed phenomenon in the left portal branch, and have provided reference ranges for single observations and serial measurements. Copyright (c) 2007 ISUOG
OBJECTIVES: The left portal vein represents a watershed area in the fetal circulation and the change of flow direction is a suggested marker of circulatory compromise. Our aim was to study the left portal vein of uncompromised human pregnancies and establish reference ranges. METHODS: One hundred and sixty low-risk pregnant women were recruited to a longitudinal study that included four to five Doppler measurements at monthly intervals during the second half of pregnancy. RESULTS: Based on 554 Doppler recordings we found time-averaged maximum flow velocities increasing from a mean of 10.6 cm/s to 14.2 cm/s during 21-31 weeks of gestation, remaining stable until 37 weeks and decreasing towards term. Intermittent flow reversal occurred during fetal respiratory movements, and continuous flow reversal was seen in 2/160 fetuses close to delivery. CONCLUSIONS: We propose time-averaged maximum blood velocity measurement for quantification of the watershed phenomenon in the left portal branch, and have provided reference ranges for single observations and serial measurements. Copyright (c) 2007 ISUOG