A Hydatidiform Mole is a rare pregnancy complication that occurs when abnormal tissue grows inside the uterus instead of a normal embryo. This condition can result from an error during fertilization, leading to the formation of a mass of cysts. There are two types: complete and partial, with complete moles having no normal fetal tissue. Symptoms of a hydatidiform mole may include vaginal bleeding, rapid uterine growth, and severe nausea. Diagnosis is typically made through ultrasound and blood tests measuring pregnancy hormones. Treatment usually involves the removal of the abnormal tissue to prevent complications, such as gestational trophoblastic disease.