Placental histopathology associated with pre‐eclampsia: systematic review and meta‐analysis

OBJECTIVE: Pre-eclampsia (PE) is associated with impaired trophoblastic invasion and typical villous and vascular placental lesions. The primary aim of this study was to quantify the prevalence of placental histopathological lesions in pregnancies complicated by PE. METHODS: statistic. RESULTS: The search yielded 717 citations, and a total of eight studies (four blinded and four non-blinded) were included in the review. In unblinded studies, the pooled prevalence of villous lesions was 11.6% and 48.2% in normal and pre-eclamptic pregnancies, respectively, giving a pooled odds ratio (OR) of 7.59. In blinded studies, the pooled prevalence of villous lesions was 18.5% and 42.0% in normal and pre-eclamptic pregnancies, respectively, giving a pooled OR of 4.28. In unblinded studies, the pooled prevalence of vascular lesions was 8.1% and 37.3% in normal and pre-eclamptic pregnancies, respectively, giving a pooled OR of 20.34. In blinded studies, the pooled prevalence of vascular lesions was 9.8% and 38.9%, in normal and pre-eclamptic pregnancies, respectively, giving a pooled OR of 7.08. CONCLUSIONS: In blinded studies, the incidence of both placental villous and vascular histopathological lesions is four- to seven-fold higher in pre-eclamptic than in normal pregnancies. Greater differences are reported in unblinded studies. Despite the higher probability (point prevalence) of finding abnormal placental pathology in pregnancies with PE, placental lesions are not specific to the diagnosis of PE.