Blood flow velocity in the uterine and external iliac arteries before and after termination of pregnancy

Abstract

In normal pregnancy, there is a marked increase in the uteroplacental blood flow, which is accomplished by a decrease in the peripheral resistance. The purpose of the present study was to investigate whether changes occur in the uterine and external iliac arteries during early pregnancy and after termination of pregnancy. Twenty pregnant women between the 7th and the 23rd weeks of pregnancy were investigated. They were examined before termination of pregnancy and followed up after the termination. The examinations were done using a pulsed duplex scanner (Acuson model 128XP/10 computed sonography system). In the right and left uterine arteries, there is a close correlation between both the peak flow velocity ( r = 0.84; P < 0.01) and the end diastolic flow velocity ( r = 0.71; P < 0.01) and the duration of pregnancy. The V max and V min in the external iliac arteries did not significantly change. The peak flow velocity ( V max) in the right uterine artery was gradually reduced after termination of pregnancy. It was 0.81 (0.22) m/s before termination of pregnancy, reduced to 0.72 (0.22) m/s in the 1st post-operative day, and to 0.68 (0.21) m/s in the 2nd post-operative day. There was also a significant decrease of the end-diastolic flow velocity ( V min), from 0.24 (0.10) m/s before termination of pregnancy to 0.15 (0.08) m/s in the 1st post-operative day. The left uterine artery showed similar changes. There is a strong correlation between V max and V min in both uterine arteries (in the right r = 0.71; in the left r = 0.57) indicating an influence on resistance indices. Compliance and resistance of the uterine arterial vascular bed is reflected by the end-diastolic flow velocity. They start to change at a very early gestation. The resistance indices gave poor information concerning these changes since both V max and V min increase simultaneously.