What is a hydatidiform mole?

Some women may notice delayed menstruation and symptoms resembling early pregnancy; however, upon examination, no normally developing fetus is found in the uterus. This situation understandably raises significant concern for any woman—what could be causing it? The underlying cause is a molar pregnancy (hydatidiform mole), which most commonly occurs in women of childbearing age. If not treated promptly, it may progress to a malignant tumor. Below, we provide a detailed overview of what a molar pregnancy is.

What Is a Molar Pregnancy?

A molar pregnancy refers to an abnormal growth in the uterus where no viable fetus develops; instead, clusters of fluid-filled vesicles of varying sizes form. These vesicles are connected by stalks and resemble grapes in appearance—hence the term “molar pregnancy” (literally “grape-like mole”). Women of reproductive age are susceptible to molar pregnancies, with the highest incidence observed among pregnant women aged 20–30 years. Molar pregnancies are classified into two types: partial and complete molar pregnancies. They result from abnormal fertilization—typically due to chromosomal abnormalities in the fertilized egg—and their development is associated with factors including maternal health status, nutritional status, and environmental influences.

What Should You Do If You Experience Symptoms of a Molar Pregnancy?

Once diagnosed, a molar pregnancy requires prompt therapeutic intervention. Prior to treatment, baseline assessments—including chest X-ray, electrocardiogram (ECG), and routine blood tests—are essential. The primary treatment options include the following four approaches:

(1) Vacuum Aspiration and Curettage

This is the most effective and safest treatment method. The aspirated tissue is sent for histopathological examination to determine whether the lesion is benign or malignant. Intravenous oxytocin or other uterotonic agents are administered during the procedure to promote uterine contraction. However, caution is critical: the uterus in molar pregnancy is unusually soft, making it highly susceptible to perforation during uterine sounding, vacuum aspiration, or curettage.

(2) Hysterectomy

Hysterectomy may be considered for older patients or those who have completed childbearing. Nevertheless, because molar pregnancies often cause marked uterine vascular engorgement, surgeons must remain vigilant for intraoperative hemorrhage. Importantly, gestational trophoblastic disease (GTD) may still develop post-hysterectomy; therefore, long-term follow-up remains mandatory.

(3) Hysterotomy

This surgical approach involves opening the uterus to directly remove the molar tissue.

(4) Medical Induction of Abortion

The latter two methods—hysterotomy and medical induction—carry a higher risk of trophoblastic cell dissemination and are therefore rarely employed. Typically, serum human chorionic gonadotropin (hCG) levels return to normal within 2–3 weeks after spontaneous or induced abortion. In contrast, following molar pregnancy treatment, hCG normalization usually takes 2–3 months. Among patients with complete molar pregnancies, approximately 80% achieve full remission, 15% develop invasive mole, and 5% progress to choriocarcinoma.

The above provides a comprehensive explanation of what a molar pregnancy is. We hope this information proves helpful.