What treatments can be done through an ercp scope?

Many. Treatment probably includes diagnosis as well as therapy. Structures can be 'illuminated', tissue can be obtained (biopsies for pathologist to examine), bleeding can be halted, stones removed, areas of narrowing opened. How's that for starters? It can also be done as a complement to other studies to complete the evaluation process. If you've been offered one, you must discuss the rationale...
See list. 1.) removal of stones 2.) placements of stent 3.) biopsies 4.) stopping bleeding 5.) duct brushing.