DETERMINATION OF INTERVILLOUS FLOW IN EARLY-PREGNANCY

The process of placentation in the macaque has been extensively studie d and found to resemble closely that observed in the human. In this mo del, histopathologically, intervillous flow is anticipated from week 3 post-conception. We set out to document the nature and onset of inter villous flow in the macaque in vivo using colour Doppler imaging (CDI) , colour Doppler energy (CDE) and pulsed-wave Doppler (PWD). Pregnant females were assessed between 15-50 days gestation (term=165 days) wit h an Acuson 128/XP10 high-resolution ultrasound scanner, using a 7-MHz linear array probe. The placenta, subjacent decidua and myometrium we re assessed using CDI and CDE. Specific regions of flow were interroga ted using PWD; the resulting flow velocity waveforms were stored and q uantified using conventional Doppler indices. B-mode sonography was ab le to demonstrate the well-defined placental-decidual interface observ ed in this species; CDI and CDE clearly visualized the uteroplacental vasculature. Spiral arteries were follow-ed to their point of discharg e into the intervillous space, and PWD at these sites obtained a chara cteristic flow velocity waveform. The indices obtained confirmed a flo w of low resistance and pulsatility throughout the gestation studied. Flow within the intervillous space was noted from day 20 of gestation. (C) 1997 W. B. Saunders Company Ltd.