Doppler ultrasonographic features of the developing placental circulation: Correlation with anatomic findings Eric Jauniaux, MD, Davor Jurkovic, MD, Stuart Campbell, MD, Jean Hustin, MD, PhD London, England, and Loverval, Belgium Color Doppler was used to study the placental circulations of 28 pregnancies between 10 and 17 weeks' gestation. A histomorphometric investigation was performed on placental tissue samples from those pregnancies, and the results were compared with Doppler features. Important changes were found around 14 weeks' gestation in both uterine and umbilical circulations. The appearance of end-diastolic frequencies in the umbilical arteries was related to an abrupt and significant (p < 0.005) increase in uterine velocity and to the establishment of a continuous intervillous circulation. (AM J OBSTET GVNECOL 1992;166:585-7.) Key words: Doppler ultrasonography, placental circulation, early pregnancy The beginning of fetal life is associated with re- markable hemodynamic changes in the placental cir- culations. During the first 3 months of gestation, the growing embryo is separated from the maternal cir- culation by the trophoblastic shell.' The tips of the spiral arteries are obstructed by intravascular tropho- blastic plugs, and the intervillous space is bathed by a clear fluid, possibly made of filtered plasma and uterine gland secretions. The spiral arteries widen pro- gressively, and around 12 weeks' gestation the tropho- blastic plugs are eventually loosened and dislocated, allowing free blood circulation in the intervillous space.' The purpose of this study was to investigate Doppler flow velocity waveform characteristics in the placental circulation between IO and 17 weeks' gestation and to correlate these with anatomic features of placental vas- cular development. Material and methods Twenty-eight pregnant women between 10 and 17 weeks' gestation were investigated, four cases for each gestational week between 12 and 15 weeks and three for each of the other weeks. All were referred for ul- trasonographic examination before termination of pregnancy for psychosocial reasons. Only patients who were certain of their last menstrual period, who were not using oral contraceptives, and who had never smoked were included in the study. All pregnancies were clinically uncomplicated, and ultrasonographic measurement of crown-rump length or biparietal di- ameter was within the normal range for gestational age. From the Department of Obstetrics and Gynecology, King's College School of Medicine and Dentistry, and the Histopathologic Institute. Received for publication january 28, 1991; accepted July 16, 1991. Reprint requests: Eric jauniaux, MD, Department of Obstetrics and Gynecology, Academic Hospital Erasme, 808 route de Lennik, 1070 Brussels, Belgium. 6/1/32432 After giving informed consent, each woman under- went Doppler examination with 5.0 MHz curvilinear transvaginal probe with pulsed and color Doppler fa- cilities (Aloka Color Doppler SSD-680, Aloka Co., Tokyo). The high-pass filter was set on 100 Hz and the pulse repetition frequency was 2 to 12 kHz. Color Doppler was used to identify vessels of interest and served as a guide for pulsed Doppler velocimetry stud- ies. In each case flow velocity waveforms were obtained from both main uterine arteries at the level of the in- ternal os, from spiral arteries at the level of the pla- cental bed, and from umbilical cord arteries. The in- traplacental areas of color flow were also investigated by spectral Doppler analysis. Simultaneous color im- aging made it possible to obtain the maximum peak velocity in the uterine artery by positioning the trans- ducer so that the angle between the pulsed Doppler beam and the vessel was close to zero. Uterine flow velocity waveforms were standardized by means of the resistance index, calculated as the mean obtained from three waveforms of satisfactory quality and averaged for both sides. Terminations of pregnancy were performed within 2 hours after Doppler ultrasonographic investigations. In each case samples of placental tissue were obtained by aspiration and were immediately immersed in for- malin. After 3 days of fixation the specimens were embedded in paraffin, sectioned at 4 fLm intervals, and stained with hematoxylin and eosin for histologic ex- amination. The sections were viewed with an immer- sion objective, connected to a video system. Twenty normally trophic, stem villi were examined at random for each case. A point-counting grid was superimposed onto the image, and the fraction of the villous surface (percent) occupied by the fetal vessels was estimated by test point counting. The number of vessel profiles per villous profile was also calculated. The relationships between gestational age and Dopp- ler and histologic data were analyzed by simple regres-