## **Core Concept**
The management of ectopic pregnancy depends on several factors including the patient's hemodynamic stability, the size of the adnexal mass, and the level of beta-human chorionic gonadotropin (β-hCG). Medical management is often considered for patients who are hemodynamically stable with certain criteria.

## **Why the Correct Answer is Right**
For a hemodynamically stable patient with an ectopic pregnancy, a small adnexal mass (<3.5 cm), and a β-hCG level <5000 mIU/mL, medical management with methotrexate is often suitable. Methotrexate works by inhibiting dihydrofolate reductase, which is necessary for DNA synthesis and cell division. Since the rapidly dividing trophoblastic cells require folic acid for growth, methotrexate effectively terminates the pregnancy. Given the patient's β-hCG level of 1500 mIU/mL and an adnexal mass of 2.5 x 3 cm, methotrexate is a reasonable treatment option. ## **Why Each Wrong Option is Incorrect** - **Option A:** Surgical management is generally reserved for patients who are hemodynamically unstable, have a larger adnexal mass, higher β-hCG levels, or have failed medical management. This patient is stable, making surgery not immediately necessary. - **Option B:** Expectant management involves monitoring the patient with serial β-hCG levels and ultrasounds, typically considered for patients with very low β-hCG levels (<200 mIU/mL) and no significant symptoms. A β-hCG of 1500 mIU/mL is too high for expectant management alone. - **Option C:** (Assuming this is another incorrect option, as the actual options are not provided) If another option suggests a combination or a different treatment, it would be incorrect based on the specifics provided (e.g., another medical treatment not typically used for ectopic pregnancy). ## **Clinical Pearl / High-Yield Fact** A key point to remember is that methotrexate is most effective when the β-hCG level is <5000 mIU/mL and the adnexal mass is small (<3.5 cm). Patients must also be hemodynamically stable and have no significant symptoms. Monitoring includes serial β-hCG levels to assess treatment response. ## **Correct Answer:** . Methotrexate.