Gestational Trophoblastic Neoplasia Follow-up
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Direct answer
Follow-up after molar pregnancy is the serial hCG chart: weekly values until normal, then monthly — commonly for six months after normalisation for an uncomplicated molar pregnancy, extended after chemotherapy for treated disease, and up to two years in many high-risk protocols because late relapses cluster early but do occur. The chart decides everything: a plateau or rise re-enters the patient into the treatment pathway, while a normal curve leads to discharge with strict contraception — barrier or progestogen methods preferred, with the combined pill traditionally delayed until hCG normalises. Every subsequent pregnancy deserves an early ultrasound and an hCG check around six weeks after delivery, because the risk of a second mole after one molar pregnancy is about 1–2%, and choriocarcinoma can follow any pregnancy — term, abortion or ectopic.
What you must remember
- Plateau: four hCG values within about 10% across three weeks; rise: three consecutive weekly increases; persistence at six months post-evacuation historically triggered chemotherapy, though modern protocols watch a clearly falling value.
- hCG above 20,000 IU/L beyond four weeks after evacuation prompts early treatment because of uterine perforation risk.
- Contraception is mandatory and documented: progestogen or barrier methods; the combined oral contraceptive has traditionally been avoided until hCG normalises, though modern data are largely reassuring; no intrauterine device until hCG is normal.
- Registration with a specialist trophoblastic disease centre is standard — the UK model of centralised registration and follow-up is the template Indian tertiary practice increasingly borrows.
- A rising hCG during follow-up is a pregnancy until excluded: ultrasound first, because treating "relapse" in a pregnant patient with chemotherapy is the catastrophe this rule prevents.
- Phantom hCG: heterophile antibodies produce a false-positive serum hCG that is negative in urine — serum positive with urine negative means a reference laboratory, not chemotherapy.
- Relapse occurs in a few per cent, mostly within the first year; modest late risks after multi-agent chemotherapy include second malignancy and early menopause.
- Anti-D is given to Rhesus-negative women at evacuation; theca-lutein cysts are followed conservatively; thyroid function is checked if hyperthyroid features emerge from high hCG.
Reading the chart
Walk three charts aloud in a viva. The first falls week by week in log-linear fashion from 100,000 to undetectable over twelve weeks after evacuation and continues monthly for six months — an uncomplicated mole, discharged. The second plateaus at ten weeks: 3200, 3350, 3100, 3250 across 21 days — four values within 10%, which is post-molar GTN, and the patient moves to scoring and single-agent methotrexate. The third belongs to a woman discharged a year ago whose hCG now reads a modest 90 IU/L, static across three samples, with a negative urine pregnancy test — phantom hCG from heterophile antibodies, resolved by sending sera to a reference laboratory rather than by starting chemotherapy. Between the second and third sits the rule that ties the topic together: rising hCG, ultrasound first; static low hCG, urine first.
Where students slip
The three slips: treating a rising hCG as relapse before excluding pregnancy — a scan takes minutes and saves a uterus; accepting serum hCG at face value when values are low and static, forgetting that heterophile antibodies masquerade as hCG but never appear in urine; and losing patients to follow-up after the first normal value. The registration systems of trophoblastic centres exist precisely because GTN is one of the few cancers in which structured surveillance is as curative as treatment, and the candidate who says so — with the six-month and two-year conventions — has read the topic properly.
Frequently asked questions
How long is hCG followed after molar evacuation?
Weekly until normal, then monthly — commonly six months after normalisation for an uncomplicated mole, and up to two years after high-risk chemotherapy in many protocols.
Which contraception is advised during follow-up?
Barrier or progestogen methods; the combined pill is traditionally delayed until hCG normalises, and intrauterine devices wait until normal hCG and uterine involution.
What are the rules for pregnancy after a molar gestation?
Pregnancy is best deferred until follow-up completes; then early ultrasound confirms normal gestation, and hCG is checked about six weeks after delivery to exclude recurrent disease.
What is the risk of a second molar pregnancy?
About 1–2% after one mole, rising steeply after two — a history of repeated moles argues for referral for familial disease assessment.
What should be done first when hCG rises during follow-up?
A pregnancy test and pelvic ultrasound — ordinary pregnancy is the commonest cause of rising hCG in follow-up and must be excluded before relapse is diagnosed.
What is phantom hCG?
A false-positive serum hCG caused by heterophile antibodies, negative on urine testing; it is resolved by reference-laboratory assays, never by chemotherapy.