In this study, CD31 was used to visualize intact fetal vessels within placental villi as shown in Fig. 3a (red fluorescence) or leakage of fetal blood to the maternal circulation in the case of the chorangioma with evidence of a fetomaternal transfusion site as shown in Fig. 3b with incomplete CD31 vessel staining. Here, PECAM1 is linked to placental hemangioma.