Effect of surgical stress on the distribution of placental blood flows

The distribution of the uterine and umbilical blood flows over the surface of the placenta was measured in 9 near-term sheep in an effort to assess the effects of surgical stress. The blood flows were observed to be relatively evenly distributed over the surface of the placenta. It was determined that the heterogeneity of distributions observed in the study could have caused the transplacental clearance of a very diffusible molecule to decrease by no more than 2%. It is concluded that at the macroscopic level, in both the acute and chronic conditions, the uterine and umbilical blood flows of the near-term sheep are relatively evenly distributed over the surface of the placenta and that this distribution per se does not significantly contribute to transplacental concentration gradients.