Placental Insufficiency

Excerpt

Placental insufficiency is associated with various obstetric disorders such as pre-eclampsia and intrauterine growth restriction (IUGR), both of which predispose to preterm labor, a leading cause of perinatal morbidity and mortality around the world. Poor placental function is most commonly described by the term placental insufficiency within the medical community; however, 1 study highlighted the problem of no standardized definition or consensus for the pathognomonic features of placental insufficiency.

This poses many challenges when studying placental insufficiency in the literature. Still, the general understanding is that placental insufficiency is a progressive deterioration in placental functioning. Oxygen and nutrient transfer to the fetus via the placenta is decreased, culminating in decompensated hypoxia and acidosis. This process leads to fetal hypoxemia that then stimulates a downregulation of fetal metabolic demands to preserve what nutrients are already accessible, thus resulting in intrauterine fetal growth restriction. From a histopathologic view, placental insufficiency can be defined when there is chorionic villi fibrosis, uteroplacental thrombosis, placental infarcts, fibrin deposits, or a reduction in the number and surface area of the villous capillary tree. Placental infarcts can be a normal finding, as they are observed in approximately 25% of normal-term pregnancies; however, increasing infarction of the placenta is associated with placental insufficiency and, thus, IUGR. MRI and ultrasound studies looking for placental insufficiency have demonstrated reductions in placental area and volume, increased placental thickness, and globular-shaped placentas on MRI.