can I bill both the ICU visit and a renal replacement therapy, I just started billing for nephrology so i'm confused the Dr told me that his previous biller, billed for both and he got paid for both that she used a modifier, I tried looking it up thru supercoder and it gave me codes 90935 and 90937 and it says to use modifier 25 but do I use it on every ICU visit? please help I am very confused