A 32-year-old woman (G3P2) with a history of pelvic inflammatory disease 2 years ago presents with 8 weeks of amenorrhea and mild lower abdominal discomfort. Vital signs are stable (BP 118/76 mmHg, HR 82/min). Serum β-hCG is 6,200 mIU/mL. Transvaginal ultrasound shows an empty uterine cavity and a 2.5 cm gestational sac-like structure in the left fallopian tube with yolk sac but no fetal pole. There is minimal free fluid in the pelvis. What is the most appropriate management?

Explanation

## Clinical Diagnosis This patient has an **unruptured tubal ectopic pregnancy** that is hemodynamically stable and meets criteria for medical management with methotrexate. ### Criteria for Medical Management (Methotrexate) | Criterion | Patient Status | |-----------|----------------| | Hemodynamic stability | ✓ Stable vitals | | No rupture/minimal free fluid | ✓ Minimal free fluid | | Unruptured ectopic mass | ✓ 2.5 cm, intact | | β-hCG < 100,000 mIU/mL | ✓ 6,200 mIU/mL | | Ectopic mass < 3.5 cm | ✓ 2.5 cm | | No contraindications to MTX | ✓ No renal/hepatic disease mentioned | | Patient compliance likely | ✓ Follow-up possible | **Key Point:** Medical management with methotrexate is the first-line treatment for hemodynamically stable, unruptured ectopic pregnancies with low β-hCG levels and small mass diameter. **High-Yield:** Single-dose methotrexate (50 mg/m²) is preferred over multi-dose regimens in this scenario because: - Simpler administration - Fewer side effects - Success rate 88–96% when β-hCG < 5,000 mIU/mL - Success rate 76–88% when β-hCG 5,000–10,000 mIU/mL **Mnemonic: MTX Criteria (STABLE)** — Stable hemodynamics, Tube unruptured, Absence of rupture signs, Beta-hCG low, Low mass diameter, Expects follow-up **Clinical Pearl:** The presence of a yolk sac (not fetal pole) indicates early gestation; this does NOT change the indication for medical management — it actually confirms viability of the ectopic tissue and supports MTX efficacy. ### Post-Methotrexate Follow-Up 1. **Day 4:** Check β-hCG (should decline by ≥15%) 2. **Day 7:** Repeat β-hCG (should decline by ≥15% from day 4) 3. **Weekly:** Continue β-hCG until undetectable 4. **Ultrasound:** Repeat at 1–2 weeks to confirm resolution **Warning:** Do NOT perform laparoscopy or laparotomy in a stable patient with unruptured ectopic pregnancy — this exposes the patient to unnecessary surgical risk when medical management is highly effective. [cite:Jeffcoate's Principles of Gynecology 8e Ch 14]