Hydatidiform Mole: Post-Evacuation Surveillance
A 35-year-old woman underwent uncomplicated suction evacuation of a suspected molar pregnancy after a pre-procedure beta-hCG of 180000 mIU/mL. Histopathology confirms a complete hydatidiform mole. She is now well, with no bleeding, blood pressure 118/70 mm Hg and pulse 80 beats/min. Which of the following is the surveillance protocol advised after evacuation of a hydatidiform mole?
- A.Weekly beta-hCG until undetectable, then stop follow-up
- B.Monthly beta-hCG until undetectable, then weekly for 6 months
- C.Weekly beta-hCG until undetectable, then monthly for 6 monthsCorrect
- D.Weekly beta-hCG for 6 months regardless of the level
Explanation
After molar evacuation the purpose of surveillance is early detection of gestational trophoblastic neoplasia, which follows about 15% to 20% of complete moles and 1% to 5% of partial moles. The standard protocol is weekly quantitative beta-hCG until three consecutive undetectable results are obtained, followed by monthly measurements for a further period of surveillance, classically 6 months in the ACOG teaching. Weekly testing is essential in the early phase because a plateau over four values across 3 weeks, or a rise of more than 10% across three values over 2 weeks, defines neoplasia and triggers chemotherapy. Stopping the moment hCG becomes undetectable would miss the delayed re-elevation that heralds persistent trophoblastic disease. Monthly testing from the outset is too infrequent to detect a plateau or rise in time. Reliable contraception, usually combined oral contraceptives, must be used throughout surveillance so that a new pregnancy does not confound interpretation of a rising hCG; an intrauterine device is avoided until hCG is undetectable because of perforation and bleeding risk. Chest radiography is performed if hCG plateaus or rises, since the lungs are the commonest metastatic site. Future pregnancies need early ultrasound and hCG measurement 6 weeks postpartum because the recurrence risk is about 1% to 2%.
Why each option
- A.
- Stopping at the first undetectable value forfeits detection of delayed re-elevation from persistent trophoblastic disease.
- B.
- Monthly testing first is too infrequent to identify an early plateau or rise, and reversing the order has no rationale.
- C.
- Correct. Weekly beta-hCG until undetectable, then monthly surveillance for 6 months, is the classic post-molar protocol.
- D.
- Weekly sampling for a full 6 months after normalisation is burdensome and is not what guidelines recommend.
Reference: ACOG Practice Bulletin No. 53, Diagnosis and Treatment of Gestational Trophoblastic Disease, reaffirmed 2019
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