Describe hydatidiform mole — its aetiology, clinical features and management.

Definition

A hydatidiform mole is a form of benign gestational trophoblastic disease characterised by abnormal proliferation of the trophoblast with hydropic (vesicular) swelling of the chorionic villi, so that the products resemble a "bunch of grapes".

Types

Clinical Features

Amenorrhoea followed by vaginal bleeding, a uterus large for dates, severe hyperemesis, early pre-eclampsia, expulsion of grape-like vesicles, and bilateral theca-lutein cysts.

Investigations and Management

• Ultrasound — a "snow-storm" appearance with no fetus; a very high serum β-hCG.
• Suction evacuation of the uterus, with anti-D for Rh-negative women.
• Serial β-hCG follow-up with contraception to detect persistent/malignant GTN (which follows 15–20% of complete moles).

Complications

Haemorrhage and anaemia, hyperemesis and early pre-eclampsia, hyperthyroidism (hCG cross- reactivity), trophoblastic pulmonary embolisation at evacuation, and progression to persistent/malignant GTN.

A Note on WHY a Mole Must Be Followed with Β-HCG

A vital point is understanding why evacuating a hydatidiform mole is only half the treatment — and why the follow-up is what saves lives. A mole is a benign tumour of the trophoblast, and suction evacuation cures most women. But in a proportion — about 15–20% of complete moles (and only 1–5% of partial moles) — trophoblastic tissue persists, invading the myometrium (invasive mole) or transforming into frank choriocarcinoma, which spreads early and haematogenously to the lungs and brain and is rapidly fatal if untreated. Crucially, this persistence produces no symptoms at first: the only sign is a β-hCG that fails to fall to normal, or plateaus, or rises. Hence every woman must have serial β-hCG measurements until they are normal and remain so. The reward is enormous: detected this way, persistent disease is treated with chemotherapy and cured in nearly 100% of cases, with fertility preserved. Two rules follow: effective contraception is mandatory throughout the follow-up (a new pregnancy would produce β-hCG and blind the surveillance), and the IUCD is avoided until the β-hCG is normal (risk of perforation). Understanding that the mole is followed chemically, not clinically, explains everything about its management.

Follow hCG after evacuation to detect persistent disease.

• Hydatidiform mole: abnormal proliferation of the trophoblast — complete (46XX, all paternal, no fetus, ~15–20% become malignant) or partial (triploid 69, with fetal parts, 1–5%).
• Presents with amenorrhoea then bleeding, a uterus larger than dates, hyperemesis, early pre-eclampsia, theca-lutein cysts and passage of vesicles.
• Diagnosis: markedly raised β-hCG and a 'snowstorm'/bunch-of-grapes appearance on ultrasound with no fetal parts.
• Treatment: suction evacuation (avoid oxytocics before evacuation — risk of embolisation); send for histology; give anti-D if Rh-negative.
• Follow up with serial β-hCG until normal, with mandatory contraception (avoid IUCD until β-hCG normal); a plateau or rise means GTN → chemotherapy.