Tansvaginal Color Doppler Assessment of the Spiral Artery Blood Flow in Early Pregnancy

Oh, M J; Shin, J C; Chung, D Y; Kim, S J; Han, S H; Song, J M

Abstract

OBJECTIVE
The aim of this study was to define the characteristics of the blood flow in the both uterine arteties and spiral arteries and to investigate the change of the blood flow in the uteroplacental circulation in early pregnancy using transvaginal color Doppler.
METHODS
104 pregnant women with normal intrauterine pregnancy were included in the study from April 1998 to September 1998. After confirmation of the uterine position, size morphology and gestational weeks transvaginal color Doppler was then used to visualized the uterine artery and spiral artery. The rsistance index[RI] and pulsatility index[PI] were calculated after at least five sequential good-quality waveforms were obtained. Regression analysis, t-test and ANOVA were used to derive RI and PI with gestation, and to examine the significance of the correlations between the various Doppler parameters and gestational age.
RESULTS
The mean age of women was 26 years ranging from 20 to 36 year. Gestational age was ranged from 5th to 17th week and 68 women were nullipara and 36 women were multipara. There was no significant difference in RI and PI between right and left uterine arteries in all gestational age. In the uterine arteries, there were decreased according to advancing in ther gestational age for RI[r=-0.540, p<0.001]and PI[r=-0.497, p<0.001]. Similarly, RI and PI of the spiral artery were decreased according to advancing in the gestational age[RI: r=-0.383, p<0.001; PI:r=-0.421, p<0.001]. RI of uterine artery shows an abrupt decrease around 14 weeks in gestation. But there was no significant decrease of vascular impedance of blood flow of spiral arteries around 14 weeks in gestation.
CONCLUSION
This study showed a physiologic decrease in impedence of uterine and spiral arteries according to advancing in the gestational age in early pregnancy. The establishment of the intervillous circulation seems to be a continuous progressive process rather than an abrupt event at the end of the first trimester. It remains to be established whether abnormal blood flow indices in the uteroplacental circulation identify poor outcome of early pregnancy.