Patterns of placental pathology associated with preeclampsia

Maternal vascular malperfusion (MVM) is commonly observed in early onset preeclampsia, but less prevalent in late onset preeclampsia. The purpose of our analysis was to investigate patterns of placental pathology in preeclampsia.

Electronic health records for all singleton livebirths from 2009 to 2018 at a single institution with a diagnosis of preeclampsia were obtained. Text searching was used to obtain placental data from pathology reports, including lesions of MVM, fetal vascular malperfusion (FVM), chronic inflammation (CI), and acute inflammation (AI). Placental pathology was compared based on timing of delivery and latent class analysis (LCA) was used to investigate subtypes of preeclampsia based on 22 placental variables.

728 patients were included in the analysis. Prevalence of MVM decreased with advancing gestation (95.4% at <34 weeks, 69.8% at 34-36 weeks, and 50%, ≥37 weeks; p < 0.01). LCA identified five classes based on placental pathology: (1) high grade MVM, (2) CI and FVM, (3) low grade MVM, (4) AI, (5) other. Preterm birth varied across the classes (p < 0.01), with the highest prevalence observed among the classes characterized by MVM (high grade: 87.6%; low grade: 63.0%) and the lowest prevalence among the class characterized by AI (23.5%).

Placental pathology in preeclampsia differs based on gestational age at delivery with MVM seen in nearly all early onset preeclampsia cases. Latent classes largely grouped by previously defined patterns of placental injury (MVM, CI, FVM, AI), and again revealed the highest likelihood of preterm birth in classes characterized by MVM. Results suggest there may be multiple mechanisms leading to the clinical manifestations of preeclampsia.