Placenta, villitis of unknown etiology

Villitis of unknown etiology (VUE) is a chronic inflammation of the chorionic villi that is seen both incidentally and in association with intrauterine growth restriction, premature labour, and recurrent stillbirths. The main diagnostic feature is the presence of lymphocytes and macrophages within the villous stroma. Avascular villi and perivillous fibrin are also commonly seen. No pathogenic organisms are identified, and VUE is thought to result from a maternal immune response.