A 28-year-old woman presents to the emergency department with 8 weeks of amenorrhea, unilateral left lower abdominal pain, and light vaginal spotting. Vital signs show BP 110/70 mmHg, HR 92/min. Serum beta-hCG is 3200 mIU/mL. Transvaginal ultrasound shows an empty uterus with a 2.5 cm complex adnexal mass and a small amount of free fluid in the pouch of Douglas, as marked **B** in the diagram. Which of the following is the most appropriate next step in management?
A. Expectant management with serial beta-hCG monitoring every 48 hours
B. Dilation and curettage to evacuate the intrauterine pregnancy
C. Intramuscular methotrexate 50 mg/m² with beta-hCG monitoring on days 4 and 7
D. Immediate laparoscopic salpingectomy under general anesthesia
Explanation
Why Intramuscular methotrexate is right
The clinical presentation and imaging findings are diagnostic of a hemodynamically stable ectopic pregnancy (tubal ring appearance with empty uterus and free fluid, as marked B). This patient meets all criteria for medical management with methotrexate: hemodynamically stable (BP 110/70, HR 92), beta-hCG 3200 mIU/mL (below the 5000 threshold), ectopic size 2.5 cm (below 3.5 cm limit), and no evidence of fetal cardiac activity. Methotrexate, a folate antagonist, inhibits dihydrofolate reductase and arrests rapidly dividing trophoblastic cells, with success rates of 85–90% in appropriately selected cases. Per ACOG Practice Bulletin 193 and Williams Obstetrics 26e, medical management is the preferred first-line approach in stable patients with these parameters, preserving tubal anatomy and avoiding surgical morbidity.
Why each distractor is wrong
Immediate laparoscopic salpingectomy: Surgical management is reserved for hemodynamically unstable patients, uncontrolled bleeding, ectopic >3.5 cm, fetal cardiac activity present, or severely damaged tubes. This stable patient with a small ectopic is not a surgical candidate at present.
Expectant management with serial beta-hCG: Expectant management is only appropriate when beta-hCG is already falling (<200 mIU/mL) and the patient is asymptomatic. A beta-hCG of 3200 with ongoing pain is not suitable for expectant observation.
Dilation and curettage: D&C is inappropriate and dangerous in ectopic pregnancy; the pregnancy is not intrauterine. This would delay definitive diagnosis and treatment, risking rupture and hemorrhagic shock.
High-YieldNEET PG
Ectopic pregnancy is the leading cause of first-trimester maternal mortality; tubal ectopics account for 95–97% of cases, most commonly in the ampullary portion. Medical management with methotrexate is first-line in hemodynamically stable patients with beta-hCG <5000 and ectopic <3.5 cm.
ACOG Practice Bulletin 193 — Tubal Ectopic Pregnancy 2024; Williams Obstetrics 26e
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