Incomplete or partial hydatidiform mole

**Definition:** A condition caused by the over-production of cells arising into the placenta during pregnancy. This condition is characterised by a pregnancy with abnormal placental growth in which the chorionic villi become hydropic, slight to moderate trophoblast proliferation and invasion of the uterine tissue within 10-16 weeks after conception, a placental mass, theca lutein cysts, 1-5% persistent trophoblastic disease, small uterine size for dates, and vaginal bleeding, nausea, or vomiting. This condition leads to some fetal development and a missed abortion.