COLOR DOPPLER IMAGING AND IN-VIVO ASSESSMENT OF THE ANATOMY AND PHYSIOLOGY OF THE EARLY UTEROPLACENTAL CIRCULATION

Objective: To evaluate in vivo the anatomy and physiology of the norma l early uteroplacental circulation. Design: Forty-six women were inclu ded, all of whom continued their pregnancy into the second trimester. Color Doppler was used to identify peritrophoblastic flow, and spectra l Doppler was used to analyze waveforms obtained from the different se gments of the uteroplacental circulation. Results: Flow was detected i n the spiral arteries of the peritrophoblastic region in all patients. Flow was detected within the intervillous space in only one case. Con clusions: This study demonstrated that color Doppler imaging can be em ployed as an in vivo means of studying the uteroplacental circulation. The study confirmed the in vitro findings that trophoblastic invasion of the decidual spiral arteries occurs at 5 to 6 weeks' gestation. Th e study also confirmed the fact that there is no noticeable blood flow within the intervillous space during most of the first trimester of a normal pregnancy. Both of these findings may serve to protect the ear ly gestation from the forces of arterial blood flow.