My providers (gynecologic oncologists) are sometimes called in for intra-op consults by other physicians (like general ob/gyn).
If my provider performs a procedure, or takes over, then I bill for the work done with the modifier appropriate for the exact situation (could be cosurgeon -62, could be -80 assist, could be -81 minimal assist, could be no modifier needed.) There are 100 different possibilities here.
If my provider does not perform anything, simply takes a look/exam and provides advice to the other physician, then we code that as a visit with whatever is appropriate for the status of the patient (inpt, outpt, etc) and level.