A partial mole is a type of abnormal pregnancy that occurs when an egg is fertilized by two sperm cells instead of one. This results in an abnormal placenta and the presence of both normal and abnormal fetal tissue. While some fetal development may occur, it is usually not viable, and the pregnancy often ends in miscarriage. Women with a partial mole may experience symptoms such as vaginal bleeding, abdominal pain, or an unusually large uterus for their gestational age. Diagnosis is typically made through ultrasound and blood tests measuring levels of human chorionic gonadotropin (hCG). Treatment usually involves monitoring and, if necessary, surgical removal of the molar tissue.