Partial hydatiform mole is a type of hydatiform mole characterized by abnormal hyperplastic trophoblasts and hydropic villi due to fertilization of a normal ovocyte by two spermatozoa or one abnormal spermatozoon (allowing for some fetal development), and that manifests with vaginal bleeding accompanied by nausea and frequent vomiting, hyperemesis gravidarum, hyperthyroidism and risk of spontaneous miscarriage.