Placenta morphology and absent or reversed end diastolic flow velocities in the umbilical artery: a clinical and morphometrical study

Abstract

The aim of the study was to investigate if a relation exists between absent or reversed end diastolic (ARED) flow in the umbilical artery and morphometric characteristics of the placenta. Geometric parameters were measured in the terminal villi of nine placentae, collected after a pregnancy complicated by ARED flow. Placentae from pregnancies with normal Doppler velocimetry in the umbilical artery were matched for gestational age and formed the control group. Mean placental weight in the ARED group was significantly lower than in the control group. Morphometric characteristics of the terminal placental villi did not differ substantially between the two groups before 30 weeks gestation. After 30 weeks mean villous profile cross sectional area and diameter were significantly smaller in the ARED group than in the control group. The mean profile cross sectional villous diameter in the ARED group did not differ substantially before and after 30 weeks of gestation (2287 μm 2 and 2303 μm 2, respectively). Accelerated maturation of terminal villi occurs in placentae delivered after a pregnancy with ARED flow in the umbilical artery. Morphometric characteristics are significantly different between placentae expelled after ARED velocities or after normal Doppler recordings in the umbilical artery. In ARED placentae, a significantly more uniform pattern of small villi is found compared with control placentae.