A 28-year-old woman has a serum beta-hCG of 2,400 mIU/mL with no intrauterine pregnancy on transvaginal ultrasound (discriminatory zone 1,500–2,000 mIU/mL). She is haemodynamically stable with mild left adnexal tenderness. She has no contraindications. After methotrexate 50 mg/m² IM is given, what is the expected pattern of beta-hCG before declaring treatment success?

• A Immediate decline within 24 hours of methotrexate administration by ≥50%
• B A plateau for 7 days followed by a rapid fall after a second dose is always needed
• C hCG must fall below 1,500 mIU/mL within 72 hours for single-dose protocol to be considered successful
• D An initial rise (days 1–4) followed by a fall of ≥15% between day 4 and day 7, with subsequent weekly decline to non-detectable levels ✓

Explanation

Following single-dose methotrexate for ectopic pregnancy, beta-hCG levels typically rise or plateau between days 1–4 (due to ongoing trophoblastic activity before drug effect). Treatment success is defined as a fall of ≥15% between day 4 and day 7 hCG values. If this criterion is not met, a second dose is given. Subsequent weekly monitoring confirms continued decline to non-detectable levels. An immediate 24-hour fall is not expected and should not be used as the success criterion; the day 4-to-7 comparison is the validated endpoint for the single-dose protocol.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.