What is a hydatidiform mole?

During pregnancy, women often worry about the health of their unborn baby or the possibility of fetal abnormalities. What is a hydatidiform mole?

What Is a Hydatidiform Mole?

A hydatidiform mole is a type of gestational trophoblastic disease (GTD), primarily caused by edema and degeneration of trophoblastic tissue during pregnancy. Its clinical presentation often mimics normal pregnancy. Common features include amenorrhea, uterine enlargement exceeding gestational age, and markedly elevated serum human chorionic gonadotropin (hCG) levels. Additional early-pregnancy-like symptoms—such as nausea and vomiting—may also occur. Diagnosis is typically confirmed via ultrasound imaging and quantitative serum hCG testing. Hydatidiform moles are classified into two types: complete and partial. In a complete hydatidiform mole, all chorionic villi are transformed into cystic, grape-like vesicles; no embryo or fetal tissues develop, and the uterine cavity is filled entirely with these vesicles. In a partial hydatidiform mole, only a portion of the placental tissue is abnormal, and a viable or nonviable embryo may still be present within the uterus. It is important to note that approximately 40% of spontaneous abortions involve hydropic (edematous) villi—not true hydatidiform moles.

Early symptoms of a hydatidiform mole closely resemble those of normal pregnancy—including nausea, vomiting, and loss of appetite—but tend to be more severe. Additionally, patients may exhibit signs of pregnancy-induced hypertension, such as elevated blood pressure and edema. Therefore, women should carefully monitor their symptoms following missed menses. Although the symptoms of a hydatidiform mole overlap with those of normal pregnancy, distinguishing features—such as disproportionately enlarged uterus, unusually high hCG levels, and associated preeclamptic manifestations—make differentiation possible. Women experiencing any of the above symptoms should promptly seek medical evaluation and appropriate management.

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