THE UTERINE AND SPIRAL ARTERY FLOW VELOCITY WAVE-FORMS IN EARLY-PREGNANCY - A TRANSVAGINAL COLOR AND PULSED DOPPLER STUDY

Objective: Uterine artery and spiral artery flow velocity waveforms (F VWs) were investigated by transvaginal color and pulsed Doppler in the first trimester of gestation to characterize the uteroplacental circu lation in early normal pregnancy. Methods: One hundred thirty-five low -risk singleton pregnancies between 6 and 13 weeks' gestation were inc luded in this cross-sectional study. Uterine artery and spiral artery FVWs were assessed by transvaginal color and pulsed Doppler with calcu lation of resistance indices (RI). Ten pregnancies that developed intr auterine growth retardation were excluded from construction of the ref erence ranges. Results: Uterine artery FVWs were obtained in all cases . Spiral artery FVWs were detected in 90% of cases at 6 weeks, and 100 % from 7 weeks onwards. RI of both uterine and spiral artery FVWs were significantly reduced with advancing gestation. RI of spiral artery F VWs showed a significant positive correlation with RI of uterine arter y FVWs. Of the 10 pregnancies that developed intrauterine growth retar dation, 3 had abnormal RI values for the uterine artery, and 6 had abn ormal RI values for the spiral artery at the time of examination. Conc lusions: In the first trimester, the uterine vascular resistance decre ases with advancing gestation. Measurements of spiral artery FVWs seem to have the potential to predict subsequent development of intrauteri ne growth retardation.