Light and electron microscopic study of placenta in pre-eclampsia: a trial to define underlying changes and its clinical impact

Abstract

Objectives The aim of this study was to evaluate histological changes of placental villi and blood vessels in pregnancy complicated by pre-eclampsia (PE) and their relation with clinical data. Patients and methods The study included 100 pregnant women developing PE at any time during pregnancy (PE group) and 100 pregnant women free of PE (control group). Collected data included age, gestational age, manifestations and severity of PE, neonatal birth weight (BW), and placental weight (PW). Placental tissue was obtained for light and electron microscopic examination. Results BW and PW showed a significant negative correlation with maternal BMI and the presence and severity of PE. Gestational age and development of PE were significant predictors for low PW, which is a significant predictor for low BW. Placentas of the PE group showed aggregation of syncytiotrophoblast cells, hyaline degeneration of connective tissue core, and endothelial lining of stem blood vessel; villous core was devoid of fetal blood vessel. Diffuse fibrous tissue formation, hypertrophic musculosa of stem blood vessel up to endarteritis obliterans and placental tissue bridges crossing intervillous spaces and villous arborization formed only of connective tissue with no cellular elements were observed. Electron microscopy confirmed these findings and showed attenuated blood vessels and excessive villous arborization covered with fibrin-like material. Conclusion Development of placental endarteritis obliterans with diminution of placental growth and proper invasion may underlie development of PE. Reduced PW is a reflection of this histological affection and is negatively correlated with severity of PE. Early PE is associated with more severe clinical manifestation and aggressive histological changes.