Hydatidiform Mole

Snapshot

• A 27-year-old female presents to the emergency department at 11 weeks of gestation with 2 days of vaginal bleeding and pelvic pressure, as well as multiple daily episodes of nonbloody, nonbilious emesis over the past week. The patient states the bleeding is like heavy spotting with dark purplish-colored blood. On exam the uterus is larger than expected for gestational age. An ultrasound is performed and shows a snowstorm appearance of the uterus with absence of a fetus.

Introduction

• Overview
  • a type of gestational trophoblastic disease (GTD)
    • molar pregnancies are considered premalignant
      • when malignant, are termed gestational trophoblastic neoplasia (GTN)
        • e.g., choriocarcinoma
      • originates in the placenta
        • has the potential to invade the uterus and metastasize
• Epidemiology
  • incidence
    • 66-121 per 100,000 pregnancies
  • demographics
    • higher rates in Latin American, Asian, and Middle Eastern countries
  • risk factors
    • extremes of maternal age
• history of previous mole

Classification

• Complete mole 
  • 46,XX or 46,XY
  • an empty ovum fertilized by a single sperm
    • results in duplication of paternal genetic material (all DNA is from sperm)
  • higher risk of transformation into choriocarcinoma
    • 15-20% transform
• Partial mole 
  • 69,XXX, 69,XXY, or 69,XYY 
  • a normal ovum is fertilized by 2 sperm
  • histology reveals fetal tissue with edematous villi and trophoblastic proliferation 
  • less likely to transform into choriocarcinoma
• 1-5% transform

Presentation

• Symptoms 
  • exaggeration of normal pregnancy symptoms due to extremely high β-hCG
    • hyperemesis gravidarum
      • extreme nausea/vomiting
    • vaginal bleeding
      •  “prune juice” discharge
        • due to accumulated blood in uterine cavity that has oxidized and liquified
    • pelvic discomfort
      • pain or pressure
• Physical exam
  • pelvic exam
    • uterus larger than expected for gestational age
      • more common in complete mole
    • possible adnexal mass
• possible grape-like mass in vagina

Imaging

• Transvaginal ultrasound (TVUS)
  • indications
    • β-hCG > 100,000 mIU/mL
  • findings
    • central heterogeneous mass with numerous discrete anechoic spaces
    • “snowstorm,” “cluster of grapes,” or “honeycomb” appearance on older ultrasounds
    • if partial mole
      • fetal parts and amniotic fluid
      • abnormally wide gestational sac
      • abnormal-looking placenta
    • ovarian theca-lutein cysts
• more likely in complete mole

Studies

• ↑ β-hCG (> 100,000 mIU/mL)
• complete mole > partial mole

Differential

• Normal pregnancy
  • key distinguishing factors
    • uterus sized appropriately for gestation
    • β-hCG will be within normal pregnancy range
    • uterine pregnancy visualized on ultrasound
• Miscarriage 
  • key distinguishing factors
    • β-hCG will be normal or decreased
    • uterine pregnancy visualized on ultrasound
    • +/- open cervical os on exam
• +/- vaginal passage of fetal parts

Treatment

• Medical
  • RhoGAM
    • indications
      • all Rh(D)-negative mothers with vaginal bleeding if father is Rh(D)-positive or unknown
    • modalities
      • single intramuscular or intravenous dose
• Surgical
  • suction and curettage (D&C)
    • indications
      • both diagnostic and therapeutic
        • first-line treatment for mole
        • pathology confirms diagnosis
• Follow-up
  • trend β-hCG weekly
    • indications
      • all patients with confirmed mole and/or elevated β-hCG
    • if continues to uptrend
• workup for choriocarcinoma

Complications

• Choriocarcinoma
  • malignant product of gestational contents
  • very high β-hCG that does not downtrend after surgical treatment for mole
  • can metastasize to lungs and brain
  • requires surgery and chemotherapy
• Ovarian theca-lutein cysts 
  • bilateral, multicystic ovaries, often septated
  • secondary to β-hCG stimulation
  • can cause hyperandrogenism
  • also associated with multigestational pregnancy, polycystic ovarian syndrome (PCOS), and ovulation induction due to stimulation by elevated levels of β-hCG
• Hyperthyroidism
• Preeclampsia
• Respiratory distress
  • usually secondary to trophoblastic embolization