The severity of clinical manifestations in preeclampsia correlates with the amount of placental infarction

Objective. To correlate placental histopathology, in particular ischemic changes, with the clinical severity of preeclampsia. Design. A blinded retrospective study. Setting. One Swedish hospital. Sample. One hundred and fifty-seven women with severe (n = 116) or mild (n = 41) preeclampsia and 157 normotensive women matched according to gestational-age. Methods: One senior pathologist, blinded to clinical data and group, examined all histological slides. In the statistical analyses, adjustment for gestational week was done when appropriate. Main outcome measures. Placental histopathological findings. Results: Amount of infarction increased with the severity of preeclampsia (p < 0.001). Infarction involving ≥ 5% of the placental tissue was seen in 39.7% of severe preeclampsia, 17.1% of mild preeclampsia and 5.1 % of non-preeclampsia. When comparing placentas in severe preeclampsia, mild preeclampsia and non-preeclampsia, there was an increase in the presence of any infarction (80.2%, 61.0%, vs. 20.4%). Also, there was a difference in the presence of decidual arteriopathy (35.3%, 22.0%, vs. 3.8%) and accelerated villous maturation (71.6%, 53.3%, vs. 12.6%). We found no difference in intervillous thrombosis, abruption placenta or placental weight in relation to gestational week. Conclusions. In pregnancies with mild or severe preeclampsia, a large proportion of the placentas had histological signs of pathology, in particular signs of ischemia. The pathology was similar, but more pronounced in severe compared to mild preeclampsia, suggesting mild and severe preeclampsia to have similar underlying etiology.