Molar pregnancy

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Molar Pregnancy

Gestational Trophoblastic Disease

Gestational trophoblastic disease (GTD) is a spectrum of disorders caused by abnormal proliferation of placental trophoblast. It includes:

  1. Hydatidiform mole–complete or partial (non-invasive)
  2. Invasive mole
  3. Choriocarcinoma
  4. Placental-site and epithelioid trophoblastic tumours

Invasive mole, choriocarcinoma and placental-site/epithelioid tumours are grouped as gestational trophoblastic neoplasia (GTN); cure rates exceed 90 % with modern chemotherapy.

Incidence

  • Worldwide: 0.2–2 / 1 000 pregnancies (higher in Asia and Africa).
  • South Africa: ≈ 1.2 / 1 000 deliveries.
  • Post-molar GTN develops in ≈ 20 % of complete and 4 % of partial moles.

Placental Trophoblast

  • Cytotrophoblast–proliferative stem cells
  • Intermediate trophoblast–invasive phenotype
  • Syncytiotrophoblast–secretes human chorionic gonadotrophin (hCG)

Hydropic villous swelling with trophoblastic hyperplasia produces the classical “grape-like” vesicles.

Risk Factors

  • Maternal age < 20 yr or > 35 yr
  • Previous miscarriage or molar pregnancy (1–2 % recurrence)
  • Asian or African ancestry
  • Diet deficient in vitamin A, folate or protein

Hyperthyroidism

hCG shares an α-subunit with thyroid-stimulating hormone (TSH); high hCG concentrations and a more thyrotropic isoform lead to thyroid stimulation.

  • Biochemical hyperthyroidism: up to 20 %
  • Clinical thyrotoxicosis: 5–10 %
  • Risk of thyroid storm around evacuation

Clinical Features (often Present in 1st–2nd trimester)

  • Irregular vaginal bleeding ± anaemia
  • Uterine size > dates
  • Hyperemesis gravidarum
  • Pre-eclampsia before 20 weeks
  • Theca lutein ovarian cysts
  • Passage of vesicles
  • Signs of hyperthyroidism or high-output cardiac failure
  • Respiratory distress from trophoblastic emboli or pulmonary metastases

Diagnosis

Investigation Findings
Ultrasound “Snow-storm” pattern (complete); cystic spaces with fetal tissue (partial)
β-hCG Markedly elevated; plateau or rise after evacuation suggests GTN
Histology Confirms mole and classifies GTD

Management of the Mole

  • Evacuation: ultrasound-guided suction dilatation & curettage (D&C) with oxytocin after uterine evacuation to minimise trophoblastic embolisation.
  • Anti-D immunoglobulin for Rh-negative patients.
  • Hysterectomy if family complete or uncontrollable haemorrhage.
  • Follow-up: serum β-hCG weekly until normal, then monthly for 6 months (longer if high-risk). Effective contraception is essential.
  • Chemotherapy (methotrexate or actinomycin D ± multi-agent regimens) for GTN based on FIGO risk score.

Anaesthesia for Evacuation or Hysterectomy

Pre-operative Assessment

  • Full history with focus on thyroid, cardiovascular and pre-eclampsia symptoms.
  • Investigations:
    • FBC, U&E, LFT, coagulation profile, blood group & cross-match
    • Thyroid hormones (FT₄, TSH)
    • Baseline β-hCG
    • ECG ± transthoracic echo if cardiac compromise
    • Chest X-ray if respiratory symptoms/metastatic disease
  • Optimise:
    • Volume status and anaemia
    • Pre-eclampsia–magnesium sulphate if indicated
    • Hyperthyroidism–propylthiouracil or carbimazole, β-blockade (e.g. propranolol or esmolol), iodide if surgery cannot wait, hydrocortisone 100 mg IV to block T₄→T₃ conversion in emergencies.

Intra-operative Considerations

Aspect Recommendations
Monitoring Standard ASA ± arterial line, large-bore IV; central line if haemodynamically unstable
Anaesthetic technique • Spinal/epidural safe in haemodynamically stable patients–allows early recognition of thyroid or cardiovascular decompensation • General anaesthesia (GA) preferred if severe bleeding, airway concerns, or thyroid storm risk
Induction Propofol 2–2.5 mg kg⁻¹; etomidate if unstable; avoid ketamine (sympathomimetic)
Maintenance Volatile agent with air/O₂ ± remifentanil; MAC unchanged but minimise uterine relaxation
Uterotonics Start oxytocin infusion after suction commences or once uterus empty; avoid ergometrine until blood pressure stable
β-blocker Esmolol infusion (e.g. 50–200 µg kg⁻¹ min⁻¹) blunts hyperadrenergic response and may reduce blood loss
Ventilation Low tidal volume/high FiO₂ if risk of trophoblastic emboli or pulmonary oedema

Post-operative Care

  • High-care or ICU observation for haemorrhage, cardiopulmonary compromise and thyroid storm.
  • Continue β-blocker and anti-thyroid therapy until β-hCG normalises and thyroid function stabilises.
  • Early involvement of GTD centre for ongoing surveillance.

Peri-operative Complications to Anticipate

  • Massive uterine bleeding → DIC
  • Thyroid storm (hyperthermia, tachyarrhythmia, heart failure)
  • Pulmonary trophoblastic embolism or metastases
  • Pre-eclampsia/eclampsia
  • Acute cardiomyopathy or high-output failure

Differential Diagnosis of Hyperthyroidism in Pregnancy

Primary thyroid disease Gestational causes Other causes
Graves’ disease, toxic adenoma, toxic multinodular goitre, thyroiditis Transient gestational thyrotoxicosis, multiple gestation, molar pregnancy, TSH-receptor mutation, hyperplacentosis, hyperreactio luteinalis Iatrogenic (exogenous thyroxine), struma ovarii, TSH-secreting pituitary adenoma

Links

References:

  1. Swaminathan S, James RA, Chandran R, Joshi R. Anaesthetic Implications of Severe Hyperthyroidism Secondary to Molar Pregnancy: A Case Report and Review of Literature. Anesth Essays Res. 2017 Oct-Dec;11(4):1115-1117. doi: 10.4103/aer.AER_38_17. PMID: 29284889; PMCID: PMC5735464.
  2. Tidy J, Seckl M, Hancock BW. Management of Gestational Trophoblastic Disease. Green-top Guideline No. 38. BJOG. 2021;128:e1–e27. tjodistanbul.org
  3. Badlaeva A, et al. Hyperthyroidism Associated with Gestational Trophoblastic Neoplasia: Systematic Literature Review and Pathways Analysis. Cancers. 2025;17:1398. mdpi.com
  4. Hydatidiform Mole. StatPearls [Internet]. Updated 2025. ncbi.nlm.nih.gov
  5. NHS Scotland. Gestational Trophoblastic Disease (Molar Pregnancy) Guideline. 2023. rightdecisions.scot.nhs.uk
  6. Hydatidiform Mole–Treatment & Management. Medscape Reference. Updated 2024. emedicine.medscape.com

Summaries:

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© 2025 Francois Uys. All Rights Reserved.

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