A 28-year-old woman presents with 7 weeks amenorrhea and mild vaginal spotting. Transvaginal ultrasound shows an empty uterus with a thin endometrium and no adnexal mass. Serum β-hCG is 800 mIU/mL. Repeat β-hCG after 48 hours is 950 mIU/mL. What is the most likely diagnosis?
- A Failed intrauterine pregnancy (miscarriage)
- B Early viable intrauterine pregnancy
- C Complete hydatidiform mole
- D Ectopic pregnancy ✓
Explanation
This scenario describes a pregnancy of unknown location (PUL) with a suboptimal β-hCG rise. A normal early pregnancy should show a ≥53% rise in 48 hours. A rise of only 19% (800 to 950) is abnormal and most commonly indicates an ectopic pregnancy. Failed miscarriage typically shows a declining β-hCG. A viable IUP would show an appropriate rise. Complete mole would have markedly elevated β-hCG and characteristic ultrasound findings. The discriminatory zone (β-hCG 1,500-2,000 mIU/mL with TVUS) has not been reached, but the abnormal rise pattern is concerning for ectopic.
Reference: ACOG Practice Bulletin No. 193: Tubal Ectopic Pregnancy, 2018 (reaffirmed 2023) ed.
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Written and medically reviewed by the StethoPrep medical team.