PYELOSCOPY, retrograde, of one collecting system, being a service to which item 36652 applies, plus 1 or more of extraction of stone from the renal pelvis or calyces, or biopsy or diathermy of the renal pelvis or calyces, not being a service associated with a service to which item 36656 applies to a procedure performed in the same collecting system (Anaes.) (Assist.)