A 26-year-old woman presents with a 6-week amenorrhoea and mild left iliac fossa pain. Serum β-hCG is 2200 mIU/mL. Transvaginal ultrasound shows no intrauterine gestational sac and a small left adnexal mass. She is haemodynamically stable. She is managed with single-dose methotrexate 50 mg/m². Follow-up serum β-hCG on Day 4 is 2400 mIU/mL and on Day 7 is 1900 mIU/mL. This result indicates:

• A Treatment failure — repeat methotrexate or surgery required
• B Possible concurrent intrauterine pregnancy
• C Rupture of ectopic — immediate surgery
• D Treatment success — expected hCG rise then fall pattern ✓

Explanation

Following single-dose methotrexate for ectopic pregnancy, a paradoxical rise in β-hCG on Day 4 compared to Day 1 is expected (occurs in ~20–65% of cases) due to continued trophoblastic activity before the drug takes full effect. The critical assessment is the Day 4 to Day 7 drop: a fall of ≥ 15% from Day 4 to Day 7 indicates treatment success. Here, the fall from 2400 to 1900 = 500/2400 = ~21% fall, confirming successful response to single-dose methotrexate.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.