Figure 3.

Correlations between in vivo pulsatility and resistance indices (PI and RI) and flow-mediated vasodilatation (FMVD)

FMVD, assessed as the percentage decrease in fetal-inflow hydrostatic pressure (FIHP) from peak FIHP to the new steady state following an elevation in flow, was measured in normal (n = 10; A and B) and FGR placentas (n = 8, as RI and PI data cannot be obtained from two cases with absent or reversed end-diastolic flow; C and D) during ex vivo dual perfusions at a flow rate of 6 ml min⁻¹ and correlated with the umbilical artery Doppler pulsatility index (PI) (A and C) and resistance index (RI) (B and D) using the Pearson correlation coefficient. Two FGR cases had absent end-diastolic flow in the umbilical artery, preventing their inclusion.