Placental Findings in Preterm and Term Preeclampsia: An Integrative Review of the Literature

Abstract

Introduction Preeclampsia (PE) is a pregnancy complication associated with increased maternal and perinatal morbidity and mortality. The disease presents with recent onset hypertension (after 20 weeks of gestation) and proteinuria, and can progress to multiple organ dysfunction, with worse outcomes among early onset preeclampsia (EOP) cases (< 34 weeks). The placenta is considered the root cause of PE; it represents the interface between the mother and the fetus, and acts as a macromembrane between the two circulations, due to its villous and vascular structures. Therefore, in pathological conditions, macroscopic and microscopic evaluation can provide clinically useful information that can confirm diagnosis and enlighten about outcomes and future therapeutic benefit. Objective To perform an integrative review of the literature on pathological placental findings associated to preeclampsia (comparing EOP and late onset preeclampsia [LOP]) and its impacts on clinical manifestations. Results: Cases of EOP presented worse maternal and perinatal outcomes, and pathophysiological and anatomopathological findings were different between EOP and LOP placentas, with less placental perfusion, greater placental pathological changes with less villous volume (villous hypoplasia), greater amount of trophoblastic debris, syncytial nodules, microcalcification, villous infarcts, decidual arteriolopathy in EOP placentas when compared with LOP placentas. Clinically, the use of low doses of aspirin has been shown to be effective in preventing PE, as well as magnesium sulfate in preventing seizures in cases of severe features. Conclusion The anatomopathological characteristics between EOP and LOP are significantly different, with large morphological changes in cases of EOP, such as hypoxia, villous infarctions, and hypoplasia, among others, most likely as an attempt to ascertain adequate blood flow to the fetus. Therefore, a better understanding of the basic macroscopic examination and histological patterns of the injury is important to help justify outcomes and to determine cases more prone to recurrence and long-term consequences.

Placental pathology of preeclampsia from a clinical point of view: Correlation between placental histopathology, clinical signs of preeclampsia and neonatal outcome

“…The two onset‐dependent subtypes of PE have many similarities at the microscopic level, but distinguishing histological features seem to point out to the fact that EO‐PE and LO‐PE are two distinct entities (Table 2). Our findings regarding histological differences of EO‐PE versus LO‐PE are similar to several earlier observations 19 …”

“…Our findings regarding histological differences of EO-PE versus LO-PE are similar to several earlier observations. 19 The exact pathogenesis of PE is not completely understood, but several mechanisms leading to PE have been identified. In EO-PE, incomplete trophoblast invasion and inadequate remodeling of maternal spiral arteries are the main pathogenetic elements, 20 whereas LO-PE is considered to be induced by placental maturation: that is, placental hypoxia is caused by altered blood flow in the placenta, and specific maternal factors contribute to systemic signs and symptoms of PE.…”

The preventive effect of low-dose aspirin in a PPAR-γ antagonist treated mouse model of preeclampsia

“…Previous literature reports examination of the preeclamptic placenta reveals numerous placental infarcts and arterial sclerosis. Infarction may be due to maternal vascular malperfusion [ 17 , 18 ]. Placental hypoperfusion may lead to placental ischemia and contribute to the development of preeclampsia.…”

The Placenta and its Underestimated Role in Clinical Practice and Research

“…These findings also support increased risk of recurrence and long term consequences for women, such as increased risk of cardiovascular disease later in life. 8 …”

“…These findings also support increased risk of recurrence and long term consequences for women, such as increased risk of cardiovascular disease later in life. 8 In research, the placenta has a great potential and is rising as a novel resource for explaining underlying causes of adverse outcomes. Advances in molecular biology, cellular isolation and immune assays have enabled such advances.…”