A 28-year-old woman, 6 weeks amenorrheic, presents with sudden onset unilateral lower abdominal pain and vaginal spotting. Her last menstrual period was 6 weeks ago. Her blood pressure is 90/60 mmHg, heart rate 105 bpm. A urine pregnancy test is positive. What is the most appropriate next diagnostic step?

The correct answer to the question "A 28-year-old woman, 6 weeks amenorrheic, presents with sudden onset unilateral lower abdominal pain and vaginal spotting. Her last menstrual period was 6 weeks ago. Her blood pressure is 90/60 mmHg, heart rate 105 bpm. A urine pregnancy test is positive. What is the most appropriate next diagnostic step?" is Option A: Pelvic ultrasound.

The other options — B) Quantitative beta-hCG, C) Laparoscopy, D) Dilation and curettage — are incorrect for this USMLE Exam Prep question. As explained above: Given the symptoms (amenorrhea, pain, spotting, positive pregnancy test) and hemodynamic instability suggestive of rupture, an ectopic pregnancy is highly suspected. A transvaginal pelvic ultrasound …