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

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.

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.

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.

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.