A 31-year-old woman, gravida 4, para 3, aborta 0, presents at 8 weeks’ gestation with...

A molar pregnancy (gestational trophoblastic disease) is the most likely diagnosis because the β-hCG level is markedly elevated (300,000 IU/L) for an 8-week gestation, far exceeding typical levels for a normal intrauterine pregnancy. MCCQE objectives highlight that unusually high β-hCG—often accompanied by first-trimester bleeding—should raise strong suspicion for a hydatidiform mole. Bleeding is common due to abnormal trophoblastic proliferation and placental separation. A closed cervix does not exclude a molar pregnancy; it simply indicates that products of conception are not being expelled at the time of exam.

Ectopic (tubal) pregnancy more often presents with abdominal/pelvic pain and typically has lower or inappropriately rising β-hCG. Incomplete abortion usually features heavier bleeding, cramping, and an open cervix. Threatened abortion involves bleeding with a closed cervix but does not explain an extremely high β-hCG. Implantation bleeding occurs earlier (around the time of missed menses), not at 8 weeks, and would not be associated with very high β-hCG.