A 30-year-old woman is diagnosed with an unruptured ectopic pregnancy. She is hemodynamically stable, β-hCG is 1,500 mIU/mL, and transvaginal ultrasound shows a 2 cm adnexal mass without cardiac activity. She is started on single-dose methotrexate (50 mg/m² IM). On day 4, her β-hCG is 2,100 mIU/mL, and on day 7, it is 1,400 mIU/mL. What is the correct interpretation of this response?
- A Treatment is successful; continue weekly β-hCG monitoring ✓
- B Treatment has failed; proceed to surgery
- C A second dose of methotrexate is required immediately
- D The initial rise indicates a heterotopic pregnancy; perform ultrasound
Correct answer: A. Treatment is successful; continue weekly β-hCG monitoring
Explanation
With single-dose methotrexate protocol, treatment success is defined by a ≥15% decline in β-hCG between day 4 and day 7. Here, the decline is from 2,100 to 1,400 (33% decline), indicating successful treatment. An initial rise between day 0 and day 4 is common and expected due to ongoing trophoblastic activity before methotrexate takes effect. Surgery is not indicated. B second dose is considered only if the day 4-to-7 decline is less than 15%. Heterotopic pregnancy is unlikely with this clear treatment response.
Reference: ACOG Practice Bulletin No. 193: Tubal Ectopic Pregnancy, 2018 (reaffirmed 2023) ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.