What is the recommended follow-up for a patient with a partial hydatidiform mole?

Follow-Up Protocol for Partial Hydatidiform Mole

All patients with partial hydatidiform mole require serial hCG monitoring to detect persistent gestational trophoblastic disease, which occurs in 0.5-5% of cases. 1, 2

Initial Management

• Suction curettage is the preferred method for evacuation of a partial molar pregnancy 2
• Medical evacuation should be avoided 3
• Anti-Rhesus D prophylaxis should be administered following evacuation if the patient is Rh-negative 1, 2
• Hormonal contraception should be started immediately after evacuation and continued throughout the follow-up period 3

hCG Monitoring Protocol

For Partial Hydatidiform Mole (PHM)

• For triploid partial moles:
  • Measure serum hCG weekly until there are two consecutive undetectable values (<1 or <2 IU/L) 3
  • After two undetectable values, the patient can be discharged from follow-up 3

For Complete Hydatidiform Mole (CHM) or Moles Without Valid Ploidy Determination

• Measure serum hCG weekly until the value is undetectable (<1 or <2 IU/L) 3
• If serum hCG becomes undetectable within 56 days after evacuation, continue with four additional monthly measurements 3
• If serum hCG normalizes after 56 days, continue monthly measurements for 6 months 3

Indications for Chemotherapy

Chemotherapy should be initiated if any of the following occur 1, 2:

• Plateaued hCG (less than 10% fall over three measurements) or rising hCG after evacuation
• Heavy vaginal bleeding requiring transfusion
• Evidence of gastrointestinal or intraperitoneal hemorrhage
• Histological evidence of choriocarcinoma
• Evidence of metastases in the brain, liver, or gastrointestinal tract
• Radiological opacities of >2 cm on chest X-ray
• Serum hCG of ≥20,000 IU/L >4 weeks after evacuation (due to risk of uterine perforation)
• hCG detectable for longer than 6 months

Long-term Follow-up

• The risk of missed disease after completing the UK monitoring scheme is estimated at 1:2000 1, 2
• Recent evidence suggests that prolonged surveillance beyond 6 months after hCG normalization is not cost-effective and causes significant anxiety 4
• In all future pregnancies, offer an early ultrasound scan (around 8 weeks gestation) 3
• Measure serum hCG 8 weeks after termination of all future pregnancies 3

Potential Pitfalls

• Incomplete evacuation can lead to persistent disease 2
• Non-adherence to hCG monitoring protocol can lead to delayed diagnosis 2
• Some hCG assays may give false-positive or false-negative results; when results don't fit the clinical picture, measure hCG using a different assay 1
• The assay used must detect all forms of beta hCG (intact molecule, hyperglycosylated, free beta subunit, and central fragment beta subunit) 5
• Rapid transformation from hydatidiform mole to invasive mole can occur within weeks of evacuation, emphasizing the importance of strict adherence to follow-up protocols 6

Risk of Recurrence

• The risk of a further molar pregnancy after one molar pregnancy is approximately 1% 1
• In cases of recurrent or familial hydatidiform mole, genetic workup and counseling should be considered 3