Ectopic pregnancy: criteria for methotrexate vs laparoscopic salpingectomy

A 25-year-old woman with 6 weeks LMP presents with lower abdominal pain and spotting. Urine hCG positive, TVS shows a right adnexal mass of 2.8 cm with a yolk sac, no intrauterine pregnancy. Beta-hCG is 3,200 mIU/mL, hemodynamically stable. She wants to preserve fertility. What are the ACOG criteria for single-dose methotrexate vs laparoscopic salpingotomy vs salpingectomy? What serial beta-hCG levels indicate treatment failure?