Hydatidiform mole

Hydatidiform mole is a form of gestational trophoblastic disease characterized by abnormal proliferation of trophoblastic tissue and swelling of chorionic villi. It results from abnormal fertilization and is classified into two main types: complete hydatidiform mole and partial hydatidiform mole. Although most cases are benign and curable with appropriate treatment, some patients may develop persistent gestational trophoblastic neoplasia requiring chemotherapy. Careful follow-up is therefore essential after treatment.

Epidemiology

Hydatidiform mole is an uncommon pregnancy-related disorder. It occurs during reproductive age and is an important cause of abnormal pregnancy in the first and early second trimester. Early diagnosis and appropriate follow-up have significantly improved outcomes.

Risk factors

Risk factors for hydatidiform mole include:

• Previous hydatidiform mole.

• Extremes of maternal age.

• History of gestational trophoblastic disease.

• Previous spontaneous abortion.

• Nutritional deficiencies in some populations.

Pathophysiology

Hydatidiform mole results from abnormal fertilization leading to abnormal placental development and trophoblastic proliferation.

Complete hydatidiform mole

A complete mole is characterized by diffuse trophoblastic proliferation and generalized swelling of chorionic villi. There is no viable fetus or normal fetal tissue.

Partial hydatidiform mole

A partial mole is characterized by focal trophoblastic proliferation with abnormal chorionic villi and may be associated with fetal or embryonic tissue.

Excessive trophoblastic growth leads to increased production of beta-human chorionic gonadotropin (β-hCG), which is useful for diagnosis and monitoring response to treatment.

Clinical presentation

Patients commonly present during early pregnancy with symptoms related to abnormal placental growth and elevated β-hCG levels.

Symptoms

• Abnormal vaginal bleeding during pregnancy.

• Excessive nausea and vomiting.

• Passage of vesicular tissue.

• Pelvic discomfort.

• Symptoms related to enlarged uterus.

• Symptoms associated with elevated β-hCG levels.

Clinical signs

• Enlarged uterus for gestational age.

• Vaginal bleeding.

• Passage of grape-like vesicles.

• Absence of fetal heart sounds in complete mole.

• Features of pregnancy complications associated with trophoblastic disease.

Differential diagnosis

Conditions that may present similarly include:

• Missed abortion.

• Incomplete abortion.

• Threatened abortion.

• Ectopic pregnancy.

• Multiple pregnancy.

• Normal intrauterine pregnancy.

• Placental mesenchymal dysplasia.

• Gestational trophoblastic neoplasia.

Diagnostic criteria

Hydatidiform mole should be suspected in a pregnant woman presenting with:

• Abnormal vaginal bleeding.

• Excessive uterine enlargement.

• Passage of vesicular tissue.

• Markedly elevated β-hCG levels.

• Ultrasound findings suggestive of molar pregnancy.

Definitive diagnosis is established through histopathological examination of evacuated tissue.

Investigations

Laboratory investigations

• Serum β-hCG.

• Full blood count (FBC).

• Blood group and rhesus status.

• Liver function tests (LFTs) where indicated.

• Renal function tests where indicated.

Imaging studies

• Pelvic ultrasonography.

Histopathological investigations

• Histopathological examination of evacuated products of conception.

Management

Management aims to evacuate the molar tissue, prevent complications, identify patients at risk of persistent disease, and ensure adequate follow-up.

Non-pharmacological treatment

Uterine evacuation

The preferred treatment is:

• Suction curettage.

Surgical treatment

For selected patients:

• Hysterectomy.

Careful risk assessment should be performed following surgery to identify patients at increased risk of persistent gestational trophoblastic disease.

Pharmacological treatment

Patients with high-risk hydatidiform mole may require single-agent chemotherapy after surgery.

Methotrexate

• Methotrexate may be administered as single-agent chemotherapy in high-risk patients.

Actinomycin D

• Actinomycin D may be administered as single-agent chemotherapy in high-risk patients.

Management according to underlying cause

Complete hydatidiform mole

• Suction curettage or hysterectomy.

• Histopathological confirmation.

• Serial β-hCG monitoring.

• Risk assessment for persistent disease.

Partial hydatidiform mole

• Suction curettage or hysterectomy when indicated.

• Histopathological confirmation.

• Serial β-hCG monitoring.

• Risk assessment for persistent disease.

High-risk hydatidiform mole

• Surgical treatment.

• Single-agent chemotherapy with methotrexate or actinomycin D.

• Close surveillance with serial β-hCG measurements.

Referral

Refer patients to a specialist gynecologist or a center experienced in the management of gestational trophoblastic disease if:

• Diagnosis is uncertain.

• Persistent elevation of β-hCG occurs after treatment.

• High-risk hydatidiform mole is identified.

• Chemotherapy is required.

• Gestational trophoblastic neoplasia is suspected.

Complications

• Persistent gestational trophoblastic disease.

• Gestational trophoblastic neoplasia.

• Severe vaginal bleeding.

• Anemia.

• Recurrence in subsequent pregnancies.

• Rare progression to malignant trophoblastic disease.

Prognosis

The prognosis is excellent when hydatidiform mole is diagnosed early and treated appropriately. Most patients achieve complete remission following evacuation. Persistent disease can usually be successfully treated when detected early through routine β-hCG monitoring.

Prevention

There is no proven method for primary prevention. Secondary prevention focuses on:

• Early antenatal care.

• Prompt evaluation of abnormal pregnancy symptoms.

• Histopathological examination of evacuated tissue.

• Adherence to post-treatment follow-up.

• Early detection of persistent trophoblastic disease through serial β-hCG monitoring.

Follow-up

All patients should undergo:

• Weekly serum β-hCG measurement after surgery.

• Continued monitoring until serum β-hCG becomes undetectable.

Careful follow-up is essential to identify persistent trophoblastic disease and determine the need for further treatment.