O00-O08: Pregnancy with abortive outcome

O01: Hydatidiform mole

A hydatidiform mole, a form of abnormal pregnancy, is a condition where tissue that would usually grow into a fetus instead becomes an abnormal mass in the uterus. It is typically caused by issues with the egg's genetic information or the sperm. Instead of forming a fetus, clusters of blood-filled cysts develop, which can stimulate pregnancy symptoms such as missed menstrual periods, nausea, or breast tenderness. These moles can cause an abnormal elevation of human chorionic gonadotropin (HCG), a hormone usually present in pregnancy, and can be detected during routine pregnancy tests and physical examinations. As the disease progresses, some patients may experience symptoms of hyperthyroidism or preeclampsia, caused by the overproduction of HCG. Hydatidiform moles can potentially progress into a form of cancer known as choriocarcinoma, albeit this is a rarity.