I had this last year. My hcg was rising slowly and they couldn't find where the baby was growing. It worked as in i didn't end up having surgery, but it was a tense week waiting for it to work, had a blood test every 2 days and the level kept rising for a week, on the last day they kept me nil by mouth in the morning to go for the laparoscopy and at the final moment, the level plummeted - phew!
Its a gamble as some people end up having surgery too. The drug itself isnt nice and I was told i couldn't ttc for 3 months afterwards. I had a very low immune system for 6 months afterwards, literally got every bug going (I usually don't get colds etc). My skin shed like a snake too the day after the injection. No hair fell out or anything which i was worried about.
I'm glad i had it in the end as i didn't want surgery or to lose any vital bits, but its not a quick fix.
Good luck, its such a bloody awful time. So sorry you;re having to make this decision.