1. hydatidiform mole, invasive A uterine tumor derived from persistent gestational TROPHOBLASTS, most likely after a molarpregnancy (HYDATIDIFORM MOLE). Invasive hyadatiform mole develops in about 15% of patients after evacuation of a complete mole and less frequently after other types of gestation. It may perforate the MYOMETRIUM and erode uterine vessels causinghemorrhage.