Background and objective: Hemorrhagic endovasculitis (HEV) is a vasodisruptive alteration of fetal-placental blood vessels that has been associated with perinatal morbidity and mortality and abnormalities of growth and development. Clinicopathologic conditions that are often identified in pregnancies with HEV-affected placentas include villitis of unknown etiology, chorionic vessel thrombi, villous erythroblastosis, meconium staining, and maternal hypertension. The clinical implications of HEV are often disputed. This case-control study assesses the clinical relevance of HEV in placentas of viable infants and examines the interplay of coexistent intraplacental lesions.
Methods: We reviewed clinical records and slides from 104 livebirths with placentas affected by HEV above a specified severity level (cases) and 104 matched livebirths with placentas that were not affected by HEV (controls). We evaluated incidences of perinatal complications with increasing HEV severity indices in placentas with and without coexistent lesions. Interlesional relationships were established by matching HEV severity indices with severity indices of coexistent lesions. Hemorrhagic endovasculitis was subcategorized into active, bland, and healed forms and clustered capillary lesions (hemorrhagic villitis).
Results: Lesions that were frequently coexistent in HEV-affected placentas included villitis of unknown etiology, chorionic thrombi, villous fibrosis, erythroblastosis, and primary infarcts. Compared with the control group, the case group had higher incidences of abnormal fetal heart rate tracings (P <.003), fetal distress (P <.001), and growth restriction (P <.001). Increasing severities of HEV and coexistent lesions were associated with higher rates of perinatal complications. Complication rates were higher in HEV cases, with or without coexistent lesions. The complication rate was higher in cases affected by HEV and hemorrhagic villitis than in cases affected by HEV alone (P <.03). Significant interlesional relationships were evident between HEV and villitis of unknown etiology, chorionic thrombi, villous fibrosis, and erythroblastosis. CONCLUSIONS; Severe forms of HEV can occur in placentas of livebirths. The severity of HEV and associated lesions and the presence of hemorrhagic villitis have important clinical implications. Interlesional relationships between HEV and thrombotic, chronic inflammatory, and chronic vaso-occlusive lesions exist. Pregnancies with HEV-affected placentas with or without coexistent lesions are at risk for perinatal complications.