Mixed Vascular Malperfusion: A Hemodynamic Coupling Framework for Placental Vascular Injury.

Maternal vascular malperfusion (MVM) and fetal vascular malperfusion (FVM) are traditionally described as individual patterns of placental injury, each pertaining to pathology of either the uteroplacental or fetoplacental circulation. Although often identified independently, MVM and FVM may coexist in the same placenta, making strictly compartmentalized interpretation potentially incomplete. Although MVM and FVM refer to pathology within separate circulatory systems, there is anatomic and functional integration of maternal and fetal blood flow in the placenta. This structured narrative review integrates morphologic, physiologic, imaging, and biomarker data to evaluate the conceptual hypothesis that sustained maternal malperfusion may plausibly influence fetoplacental vascular dynamics and, in selected settings, contribute to histological features resembling or overlapping with FVM. We explore how altered intervillous oxygenation, villous architecture, and increased placental resistance could promote fetal endothelial activation and thrombosis, while acknowledging that evidence for true "maternal-to-fetal propagation" remains limited. Potential modifiers that may influence whether a lesion remains compartmentalized or develops overlapping features are considered; these include placental reserve, adaptive angiogenesis, cord and chorionic plate anatomy, and timing of injury. A practical approach to interpreting mixed MVM/FVM findings based on severity, distribution, chronicity, and physiological context is also outlined. We suggest that, in selected cases, interpretation of mixed placental vascular lesions may be strengthened by considering the placenta as a dual but hemodynamically coupled circulatory system.