Fetal Vascular Malperfusion.

CONTEXT: - Fetal vascular malperfusion, also known as fetal thrombotic vasculopathy, remains an underrecognized pathologic finding and should be noted during placental evaluation.
OBJECTIVE: - To review histologic findings, gain familiarity with the updated terminology, and to recognize important clinical associations with this entity. DATA SOURCES: - University of Michigan cases, PubMed search, multiple review articles including recent placental workshop group consensus statement, and selected book chapters.
CONCLUSIONS: - Multiple histologic patterns of fetal vascular malperfusion have been described including thrombosis, avascular villi, villous stromal-vascular karyorrhexis, intramural fibrin thrombi, and stem villous vascular obliteration. Various underlying etiologies can be involved in fetal vascular malperfusion. Cord lesions including abnormal insertion, length, and coiling are important causes. Maternal vascular malperfusion such as preeclampsia, hypercoagulable states, lupus anticoagulant, and sometimes diabetes have been associated with this condition. Fetal cardiac dysfunction/malformations and severe fetal inflammatory response in the setting of ascending intrauterine infection have also been attributed to this important finding. Fetal vascular malperfusion has been implicated in several significant and sometimes devastating clinical associations; these include intrauterine growth restriction, poor perinatal outcome, fetal demise, and neurodevelopmental sequelae. A diagnostic challenge may be encountered in cases with prior intrauterine fetal death, since degenerative changes post demise result in a similar histomorphologic picture. The diffuse versus the focal nature of the lesions may help in the distinction.