Synopsis
Distinguish complete from partial hydatidiform mole, recognise dangerous complications, and arrange definitive histology, specialist registration and safe follow-up without delay.
- A complete mole usually has androgenetic diploidy, no embryo or fetus, diffuse hydropic villi and diffuse trophoblastic proliferation; a partial mole is commonly diandric triploid with focal villous change and may contain fetal tissue.
- Vaginal bleeding is the common presentation, while excessive nausea, a uterus larger than dates, early-onset hypertension or clinical thyrotoxicosis are useful but increasingly uncommon clues after early ultrasound.
- Ultrasound and serum hCG can raise suspicion but cannot reliably classify every case; histopathological examination of evacuated tissue establishes the diagnosis and may require p57 or genotyping support.
- Suction evacuation is generally used for a suspected complete or partial mole when uterine preservation is intended, with senior planning for haemorrhage and anaesthetic risks.
- Send all tissue for histology and clearly state the clinical and ultrasound suspicion so pathology can distinguish mole from non-molar hydropic miscarriage.
- Register every histologically confirmed molar pregnancy with the appropriate UK trophoblastic screening centre; local negative pregnancy testing is not a substitute for central hCG surveillance.
- The risk of persistent disease is greater after complete than partial mole, but neither type can be discharged without the centre-defined confirmation schedule.
- Advise avoiding a new pregnancy until surveillance is complete because pregnancy raises hCG and prevents reliable detection of persistent trophoblast; discuss acceptable contraception and future-pregnancy support.
Key red flags
Tachycardia, hypotension, syncope, pallor or ongoing heavy bleeding suggests major haemorrhage and requires simultaneous resuscitation and urgent operative planning.
Severe headache, visual symptoms, marked hypertension or proteinuria before 20 weeks is unusual and should prompt assessment for molar pregnancy and end-organ complications.
Dyspnoea, chest pain, hypoxia or haemoptysis may reflect trophoblastic embolisation, pulmonary oedema, anaemia or metastatic gestational trophoblastic neoplasia and needs urgent escalation.
Agitation, fever, tremor, heart failure or arrhythmia with biochemical thyrotoxicosis raises concern for thyroid storm, particularly around evacuation.
Persistent or rising hCG, recurrent bleeding or new systemic symptoms after evacuation may indicate gestational trophoblastic neoplasia and must reach the specialist centre promptly.
Investigation priorities
Assess viability, placental architecture, uterine contents and adnexa in early pregnancy.
Management branches
Ultrasound, hCG or clinical features raise concern for a hydatidiform mole.
- Assess bleeding, observations, uterine size, respiratory and neurological symptoms, blood pressure and features of clinically important thyrotoxicosis.
- Obtain quantitative hCG, full blood count, blood group, renal and liver profiles and thyroid tests when indicated, with crossmatch proportional to bleeding risk.
- Ask senior gynaecology and anaesthesia to plan evacuation, explaining pregnancy loss, diagnostic uncertainty and the need for histology and later surveillance.