Chronic Marginal Placental Hemorrhage Without Placental Separation: A Layered Hematoma on MRI Mimicking Placental Tissue on Ultrasonography

Recurrent marginal placental hemorrhage may be difficult to distinguish from placental tissue on ultrasonography. We report a case of recurrent vaginal bleeding with normal amniotic fluid volume in which a large marginal hematoma was initially misinterpreted as placental parenchyma because of its similar echogenicity. T2-weighted magnetic resonance imaging revealed a four-layered hematoma with different signal intensities, demonstrating marked internal heterogeneity. After delivery, no evidence of placental separation or retroplacental hematoma was identified, while histopathology demonstrated diffuse chorioamniotic hemosiderosis. These findings suggest that chronic marginal placental hemorrhage in the absence of both placental separation and oligohydramnios may represent one pathophysiologic phenotype within the heterogeneous clinical spectrum currently termed chronic placental abruption.