title: Association of Placental Jets and Mega-Jets With Reduced Villous Density.
abstract: Spiral arteries (SAs) lie at the interface between the uterus and placenta, and supply nutrients to the placental surface. Maternal blood circulation is separated from the fetal circulation by structures called villous trees. SAs are transformed in early pregnancy from tightly coiled vessels to large high-capacity channels, which is believed to facilitate an increased maternal blood flow throughout pregnancy with minimal increase in velocity, preventing damage to delicate villous trees. Significant maternal blood flow velocities have been theorized in the space surrounding the villi (the intervillous space, IVS), particularly when SA conversion is inadequate, but have only recently been visualized reliably using pulsed wave Doppler ultrasonography. Here, we present a computational model of blood flow from SA openings, allowing prediction of IVS properties based on jet length. We show that jets of flow observed by ultrasound are likely correlated with increased IVS porosity near the SA mouth and propose that observed mega-jets (flow penetrating more than half the placental thickness) are only possible when SAs open to regions of the placenta with very sparse villous structures. We postulate that IVS tissue density must decrease at the SA mouth through gestation, supporting the hypothesis that blood flow from SAs influences villous tree development.
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand e-mail: rsag063@aucklanduni.ac.nz.
authors.forename: Rojan
authors.initials: R
authors.lastname: Saghian
authors.affiliation: Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand e-mail: j.james@auckland.ac.nz.
authors.forename: Joanna L
authors.initials: JL
authors.lastname: James
authors.affiliation: Professor Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand e-mail: m.tawhai@auckland.ac.nz.
authors.forename: Merryn H
authors.initials: MH
authors.lastname: Tawhai
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford OX3 9DU, UK e-mail: sally.collins@obs-gyn.ox.ac.uk.
authors.forename: Sally L
authors.initials: SL
authors.lastname: Collins
authors.affiliation: Auckland Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand e-mail: alys.clark@auckland.ac.nz.
authors.forename: Alys R
authors.initials: AR
authors.lastname: Clark
mesh_terms: D001158:Arteries / Q000502:physiology; D001775:Blood Circulation; D002824:Chorionic Villi / Q000098:blood supply* / Q000378:metabolism; D005260:Female; D006801:Humans; D057446:Hydrodynamics; D008954:Models, Biological; D009035:Mothers; D011247:Pregnancy