What are the signs of a molar pregnancy?

Signs of Molar Pregnancy

The classic signs of molar pregnancy include vaginal bleeding, uterine enlargement beyond expected gestational age, and markedly elevated hCG levels, with ultrasound showing characteristic "snowstorm" appearance in the uterus. 1

Clinical Presentation

Common Signs and Symptoms

• Vaginal bleeding: Most common presenting symptom, typically occurring around 6-16 weeks gestation 2
• Uterine enlargement: Uterus larger than expected for gestational age 1
• Hyperemesis gravidarum: Severe nausea and vomiting affecting 0.3-2% of pregnant women, can be associated with molar pregnancy 2
• Elevated hCG levels: Often markedly elevated, sometimes >100,000 IU/L (particularly in complete molar pregnancy) 2
• Absence of fetal heart tones: No detectable fetal cardiac activity 3

Less Common Signs

• Preeclampsia: Especially when occurring before 20 weeks gestation 2
• Anemia: Due to chronic bleeding 2, 1
• Theca lutein ovarian cysts: Bilateral ovarian enlargement 2, 1
• Hyperthyroidism: Due to cross-reactivity of extremely high hCG levels with thyroid-stimulating hormone receptors 2

Diagnostic Features by Type

Complete Molar Pregnancy (80% of GTD cases)

• No fetal parts present (all chromosomal material derived from male) 4
• More dramatic clinical presentation with:
  • Marked uterine enlargement
  • Very high hCG levels
  • Classic "snowstorm" or "bunch of grapes" appearance on ultrasound 2
  • Hydropic/swollen chorionic villi creating vesicular pattern 2
• Higher risk of progression to gestational trophoblastic neoplasia (15-20%) 1

Partial Molar Pregnancy

• May contain fetal parts (triploid conceptus) 4
• Often presents like incomplete or missed abortion 4
• Less dramatic presentation with:
  • Smaller uterine size
  • Lower hCG levels (fewer than 10% have markedly elevated levels) 2
  • Ultrasound may show focal cystic spaces within placenta, empty/elongated gestational sac, or fetal anomalies 2
• Lower risk of progression to gestational trophoblastic neoplasia (1-5%) 1

Diagnostic Workup

The National Comprehensive Cancer Network recommends:

• Pelvic ultrasound (primary diagnostic tool)
• Quantitative hCG assay (may be falsely negative on qualitative urine tests with very high levels) 5
• Complete blood count with platelets
• Liver, renal, and thyroid function tests
• Blood type and screen
• Chest X-ray 2, 1

Important Clinical Considerations

• Early diagnosis is critical as molar pregnancy can lead to life-threatening complications including hemorrhage, infection, and progression to gestational trophoblastic neoplasia
• Ultrasound findings may be subtle in early first trimester, becoming more characteristic as pregnancy advances 2
• Definitive diagnosis requires histopathological examination of uterine contents 2, 1
• False negative urine pregnancy tests can occur with extremely high hCG levels (hook effect) 5
• Ectopic molar pregnancy is extremely rare but possible, most commonly in fallopian tubes 6

Early recognition of these signs and prompt referral for definitive management with suction dilation and curettage is essential for optimal outcomes and to minimize complications.