A 32-year-old woman with a positive urine pregnancy test at home attends the antenatal clinic. She is uncertain about her last menstrual period (LMP). Transvaginal ultrasound shows a gestational sac of 8 mm with no yolk sac. What is the drug of choice for medical management if she opts for termination of pregnancy at this stage?

Explanation

## Medical Management of Early Pregnancy Termination **Key Point:** Mifepristone (progesterone antagonist) followed by misoprostol (prostaglandin analogue) is the gold-standard regimen for medical termination of pregnancy in the first trimester. ### Clinical Context At 8 mm gestational sac (approximately 5–6 weeks gestation), the patient is within the window for medical management of early pregnancy loss or termination. ### Mifepristone + Misoprostol Regimen 1. **Mifepristone 200 mg orally** — blocks progesterone receptors, leading to endometrial decidualization loss and detachment of trophoblast 2. **Wait 36–48 hours** 3. **Misoprostol 800 μg (vaginally, buccally, or sublingually)** — induces uterine contractions and cervical ripening 4. **Success rate:** 95–98% with complete expulsion ### Mechanism of Action ```mermaid flowchart TD A[Mifepristone 200 mg PO]:::action --> B[Blocks PR receptors]:::outcome B --> C[Endometrial decidualization loss]:::outcome C --> D[Trophoblast detachment]:::outcome D --> E[Wait 36-48 hrs]:::action E --> F[Misoprostol 800 μg]:::action F --> G[Uterine contractions + cervical ripening]:::outcome G --> H[Complete expulsion]:::outcome ``` ### Comparison of Regimens | Regimen | Efficacy | Timing | Advantages | Disadvantages | |---------|----------|--------|------------|---------------| | Mifepristone + Misoprostol | 95–98% | 3–7 days | Gold standard, highest efficacy, lower infection risk | Requires 2 visits, cost | | Misoprostol alone | 60–80% | 7–14 days | Single agent, lower cost | Lower efficacy, longer duration, higher bleeding | | Methotrexate + Misoprostol | 85–90% | 7–14 days | Alternative if mifepristone unavailable | Slower, teratogenic if pregnancy continues | | Oxytocin | <50% | Variable | Rarely used alone | Ineffective without cervical ripening | **High-Yield:** Mifepristone + misoprostol is the WHO-recommended first-line regimen for medical termination up to 9 weeks gestation; it has the highest efficacy and lowest complication rate. **Clinical Pearl:** The combination works synergistically — mifepristone sensitizes the myometrium to prostaglandins, making misoprostol far more effective than when used alone. **Warning:** Misoprostol monotherapy (option 2) has only 60–80% efficacy and is NOT first-line; methotrexate (option 3) is slower and reserved for cases where mifepristone is unavailable or contraindicated. **Mnemonic:** **MIM** — **M**ifepristone, **I**nterval 36–48 hrs, **M**isoprostol — the gold-standard triad for early medical termination. [cite:Williams Obstetrics 26e Ch 18; RCOG Guideline on Medical Management of Abortion]